The treatment process of cancer affects the life of an individual physiologically, psychologically, and socially. In this study, a patient who was admitted to the hematology service of a university hospital with the diagnosis of diffuse large B-cell lymphoma (Stage-IV) was evaluated. Nursing care was provided to the patient in the hospital in line with the modes of adaptation included in the Roy Adaptation Model, and the patient's adaptation with the disease and treatment process the patient needs were supported by home visits after discharge. İ.T.receivedatotalof6cyclesofchemotherapytreatment at 3-week intervals. The patient was hospitalized for 4 days for each chemotherapy cure. İ.T. was evaluated according to the four adaptation areas of the Roy Adaptation Model every day he was hospitalized. Throughout the treatment, the patient was diagnosed with nausea and acute pain in physiologic mode, deteri- oration in the body image in self-concept mode, ineffective role performance in role function mode, and changes in family processes in interdependence mode and provided with appropriate nursing interventions. By planning a home visit after each discharge, a total of 5 training sessions, each of which lasted 60 minutes, were provided for four modes of adaptation. Counseling was provided by telephone, in addition to the interview determined when needed. Written and verbal consent of the patient was obtained. According to the results of the study, positive progress was made in all Roy Adaptation Model adaptation modes of the patient who received diffuse large B-cell lymphoma, and it was concluded that the use of Roy Adaptation Model was appropriate for the systematic and holistic evaluation of the patient.