Managing children's psychological distress in the chemotherapy process is one of the essential dimensions of comprehensive care in pediatric oncology, which aims to identify, evaluate, and reduce emotional, cognitive, behavioral, and social pressures resulting from a cancer diagnosis and treatment stages. Children with cancer may experience a range of difficult experiences during chemotherapy, including fear of pain and drug complications, anxiety before medical procedures, worry about parental separation, changes in appearance, limitation of daily activities, distance from school and friends, and feelings of loss of security. The severity and manner of occurrence of this distress is not the same in all children, but is influenced by age, stage of cognitive development, personality traits, previous treatment experiences, physical condition, family support, and the quality of communication with the treatment team. From this perspective, psychological distress cannot be considered as a mere transient reaction to the hospital environment, because in some children, it may manifest in the form of persistent anxiety, irritability, isolation, sleep disturbance, decreased co-therapy, physical complaints, or decreased social and academic performance. The theoretical foundations of the management of this distress are based on a biological, psychological, and social approach and emphasize the interaction between physical processes, cognitive evaluation, emotion regulation, coping behaviors, and supportive relationships. In this framework, a psycho-oncologist is a specialist who helps to reduce psychological suffering and strengthen adaptation to the treatment process by assessing the psychological needs of the child and the family, designing interventions appropriate to the disease conditions, and collaborating with the medical team. The first specialized task of a psycho-oncologist is to identify distress early and determine its nature, severity, persistence, and aggravating factors. This evaluation should start from the time of diagnosis and initiation of chemotherapy and continue at different stages of treatment, especially before aggressive measures, after experiencing unpleasant complications, and when changing the treatment plan. Age-appropriate clinical dialogue, observation of the child's behavior, review of parental reports, and the use of valid distress assessment tools can be effective in this process. The psycho-oncologist must distinguish between expected reactions to difficult situations and symptoms that require a more specialized evaluation in terms of severity, persistence, or dysfunction. Crying, fear, or temporary refusal to take a therapeutic action is not necessarily a sign of a mental disorder, but persistent severe anxiety, panic attacks, significant withdrawal, sleep disturbance, or a noticeable decrease in the child's performance can indicate the need for targeted intervention. In this way, paying attention to the child's language and communication ability is of fundamental importance, as young children may express their distress through play, drawing, behavior changes, or physical complaints, while older children and adolescents are usually able to express some of their concerns verbally. One of the important mechanisms of distress in chemotherapy is a sense of threat and a loss of control over life events. The child may not know what will happen, how long they will stay in the hospital, or how they will be able to endure their pain and discomfort. By providing clear and honest information, appropriate to the child's developmental stage, the psycho-oncologist can reduce ambiguity and allow for a more realistic prediction of the stages of treatment. This information should be presented in simple language, in an understandable volume, and with ample opportunity to ask questions, and unrealistic promises about the absence of pain or possible complications should be avoided. When a child knows what awaits him, who cares for him, and in what areas he can choose, he is more likely to feel safe and engaged. Engaging in small, safe choices, such as choosing a distracting activity, music, or a relaxing device, can foster a sense of agency, without shifting responsibility for medical decisions to the child. Cognitive-behaviorally, distress may persist as a result of a cycle of negative anticipation, increased physical arousal, avoidance, and fear reinforcement. A psycho-oncologist can help reduce this cycle by identifying worrying thoughts, teaching coping skills, and gradually practicing emotion regulation strategies. For example, a child who expects severe pain each time before chemotherapy may experience anxiety when they see medical equipment, show more muscle tension, and feel more difficult to experience treatment. In such a situation, a combination of psychological preparation, slow breathing, mental imagery, distraction, and emotional support can help manage anxiety reactions. The choice of these methods should be consistent with the child's age, cognitive ability, physical condition, and preferences, and it is best to begin practicing skills before being in a stressful situation. Distress management also requires careful attention to pain, nausea, fatigue, and other physical symptoms, as these experiences may be interrelated with anxiety. The psycho-oncology should work with the doctor and nurse to identify symptoms requiring medical evaluation and avoid reducing the child's physical complaints to psychological problems. Inadequate control of physical symptoms can limit the effectiveness of psychological interventions, while a coordinated handling of physical and emotional needs provides a more favorable context for tolerance of treatment. Parental education is also an integral part of professional intervention, as a child's emotional reactions are formed in the context of family relationships, and parents are usually his closest source of daily support. A psycho-oncologist can teach parents how to accept a child's emotions without blaming or belittling them, answer their questions, provide age-appropriate information, and behave calmly and predictably in anxious situations. This training should not lead to feelings of guilt in parents, as their concern is also an understandable response to the child's illness and they may need psychological support themselves. In some families, economic pressures, worries about the future, responsibility for caring for other children, and difficulty in coordinating with health care facilities can reduce the capacity for emotional support, so it is important to consider family needs and refer to social services where necessary. Another area of intervention is to maintain a child's connection to their daily life and sources of identity. Chemotherapy may cause school absenteeism, reduced contact with friends, limited recreational activities, and impaired sense of continuity of life. In collaboration with the family, school, and treatment team, the psycho-oncologist can make plans to maintain social connections, adjust activities appropriate to the child's physical ability, and continue the child's meaningful experiences. Maintaining these connections does not mean ignoring medical limitations, but rather an attempt to prevent the child's identity from being limited to the disease and the role of the patient. In school-age children, a gradual return to educational activities and communication with peers can help maintain a sense of belonging if adapted to the medical situation, and in adolescents, attention to relative independence, privacy, friendships, and body image concerns becomes more important. Play therapy and art therapy are complementary methods that can provide the opportunity to express excitement and process the experience of illness. Playing with medical dolls, storytelling, painting, and creative activities allow the child to raise his questions, fears, and perceptions in a supportive environment. The role of the psycho-oncologist in these activities is to provide a safe space, facilitate the expression of emotion, and examine the meaning that the child gives to his experience personally, therefore, the content of a painting or game should not be used to draw definitive conclusions about the child's mental state. In cases where distress is associated with a history of psychological trauma, severe anxiety, depression, or complex family problems, more structured cognitive-behavioural interventions, longer professional support, or a referral to a child psychiatrist may be necessary. The psycho-oncologist should adhere to the limits of their professional competence and make the necessary coordination with relevant professionals if there is a serious risk to mental health, complex clinical symptoms, or a possible need for medication treatment. Research evidence in the field of pediatric cancer psychology supports the importance of distress screening, appropriate therapeutic communication, family involvement, and the use of psychological interventions tailored to the child's needs, however, the effectiveness of each method depends on the type of problem, characteristics of the studied population, the method of implementation, and the quality of services. Therefore, it is not possible to consider a single protocol suitable for all children and all stages of chemotherapy. One of the main challenges is the heterogeneity of children's emotional reactions and their rapidly changing needs during treatment. A child may cooperate well in one session and show more distress in the next session due to previous pain, fatigue, or worry about the results of the tests. Time constraints in health facilities, lack of trained professionals, unequal access to psychological services, and difficulty in continuous follow-up also affect the implementation of support programs. In addition, cultural and family differences, language barriers, the child's young age, and difficulty in expressing emotions directly can complicate the assessment. In future research, longitudinal review of distress changes, comparison of different interventions, measurement of functional outcomes, and study of the role of family characteristics and therapeutic environment can help to develop more accurate programs. It is suggested that pediatric cancer treatment centers establish a clear pathway for psychological screening, referral, intervention, and follow-up, and involve the psycho-oncologist in the supportive decision-making of the multidisciplinary team. Developing a mental health care plan tailored to individual needs, continuing staff training on empathetic communication, strengthening parental skills, and periodically evaluating the outcomes of the intervention can improve the quality of services. It is best to measure the outcomes of success not only by reducing anxiety, but also by the child's level of involvement, quality of life, pain experience, family adjustment, sense of control, and ability to use coping skills. Overall, the role of the psycho-oncologist in managing the psychological distress of children undergoing chemotherapy is a specialized, continuous, and multidimensional role, starting from early identification of problems to designing interventions, supporting the family, coordinating with the treatment team, and evaluating the results. The goal of this approach is not to completely eliminate the child's natural fear and discomfort, but rather to reduce preventable suffering, increase the sense of security, strengthen the ability to cope, and maintain the quality of life in difficult treatment situations. The more coordinated psychological care is with the child's developmental and individual needs and the more integrated it is with medical treatment, the more supportive it will be possible to experience the chemotherapy process with more support, active participation, and more manageable stress.