The high incidence and the severe symptoms of cancer have a considerable effect on quality of life in patients. The relationship between quality of life in patients with cancer and treatment, early diagnosis, disease acceptance, pain, psychological distress, loss of organ, duration of disease, and caregivers was investigated. This study included 508 patients with cancer treated in either inpatient or outpatient clinics of 5 oncology centers in Ankara, Turkey, between August 1998 and January 2000. Patients were selected by interviews. Data were collected by a questionnaire to determine disease features and to evaluate patients’ quality of life. We found that several disease features, including treatment, early diagnosis, disease acceptance, pain, psychological distress, and caregivers, had an effect on patients’ quality of life (P < 0.05), whereas loss of organ and duration of disease did not. The results of this study underline the significant effect of psychosocial care programs on quality of life. In the future, assessments of quality of life can help healthcare personnel to prepare psychosocial care programs.