Objectives: This study was performed as a descriptive research to determinate adherence to immunosuppressive therapy in patients undergoing renal, liver, and heart transplantation. Materials and Methods: The study sample consisted of 60 patients who underwent renal, liver, and heart transplantation and follow-up visits at a foundation university hospital. Data was collected by face-to-face interviews with transplantation patients. The immunosuppressive drugs used by the patients were compared by name, dose, prescription time, and frequency from the hospital records and adherence to immunosuppressive therapy plan was determined. Descriptive statistics, Spearman correlation coefficient, Chi-squared, and Fisher Exact tests were used for data evaluation. Results: In the study, renal transplantation was performed in 46.7% of the patients, liver transplantation in 36.7%, heart transplantation in 13.3%, and simultaneous renal-liver transplantation in 3.3%. All patients received immunosuppressive therapy and therapy adherence rate was 86.7%. A significant positive correlation was found between the total number of immunosuppressive drugs and the number of drugs used in line with the treatment plan (p