Theater therapy in patients with chronic diseases is an art and psychological approach that uses acting, role-playing, improvisation, narration, and representation of life situations to facilitate psychosocial adjustment. Its theoretical foundations are based on the assumption that chronic illness can change a person's individual, family, occupational, and social roles and affect their sense of identity and agency. Role play allows the patient to reconstruct difficult life situations in a relatively safe environment and experience them from a different angle. In this process, distancing oneself from the role of the "patient" and activating other dimensions of identity can help to redefine oneself and strengthen a sense of competence. Theater therapy also emphasizes emotional expression, social interaction, and physical experience, and can bridge between the patient's inner experience and his/her relationship with the social environment. Research evidence in the field of dramatic and participatory theater interventions has shown that these approaches can be associated with improved emotional expression, social communication, self-awareness, and some indicators of quality of life. In patients with chronic illnesses, role-playing situations such as talking to family members, facing physical limitations, returning to the workplace, or asking for help can make coping skills practical. Representing family roles also helps the patient better identify the conflict between independence and dependence and communicate more effectively about their needs. On the other hand, theater therapy can provide an opportunity to experience alternative roles; for example, a person can experience the role of a decision-maker, communicator, or person with residual abilities instead of passively experiencing the disease. This process may foster a sense of control and psychological agency. Another use is in reducing social isolation and creating the opportunity for group interaction, as dramatic activities typically require collaboration, observation, feedback, and participation. In therapy groups, the shared experience of role-playing can increase a sense of belonging and validation of the experience of illness. Theatre therapy can also be used to examine social stigma, body image changes, and concern about the judgment of others. However, the available evidence is still methodologically heterogeneous, making differences in the type of illness, the structure of the sessions, the way the intervention was implemented, and the outcomes measured, making it difficult to compare studies directly. One of the important limitations is the dependence of the results on the therapist's skill in managing emotional and group processes. Some patients may also be resistant to role-playing, revealing personal experiences, or participating in dramatic activities. Activation of painful memories or experiences associated with loss can also cause a temporary increase in distress in the absence of appropriate clinical management. Therefore, theater therapy should be conducted by a trained professional and within the framework of specific psychological goals. Initial assessment of emotional state, the patient's ability to participate, and preferences for choosing the appropriate method are important. Future research could further investigate the effectiveness of this intervention using controlled trials, larger samples, and long-term follow-up. Examining the role of theatre therapy alongside cognitive-behavioural therapies, group therapy, rehabilitation and psychosocial care could also provide more useful evidence. As a complementary intervention, theatre therapy can provide a space for reconstructing psychosocial roles, strengthening agency, expressing emotion, practicing communication, and adapting to the limitations caused by chronic disease, but its effectiveness depends on the characteristics of the patient, the structure of the intervention, and the quality of treatment delivery.