This study was designed to examine the relationship between patients' pain severity and their self-reported quality of life, to evaluate factors that may affect pain and quality of life, and to assess patients' opinions and practices on the use of analgesics. The study was conducted with 260 cancer patients. Data were collected using a Quality of Life Scale and Visual Analog Scale questionnaire. It was found that mean scores of pain, all subdomains of quality of life, and overall mean scores of patients were at a moderate level, the lowest score in the subdomains of quality of life was in the psychological subdomain and the highest was in the spiritual subdomain. It was also found that as severity of pain experienced by patients increased, their general activities, mood, activeness, sleep, and nutrition were negatively affected. As severity of pain experienced by patients increased, their quality of life worsened. Patients were observed to have insufficient knowledge and a poor understanding with respect to the use of analgesics. In conclusion, it is very important for nurses to assess factors that can complicate pain management and to establish an effective pain control.