The objective of this study was to assess disease-associated pain and quality of life (QOL) in patients with prostate cancer (PC). A total of 102 PC patients (clinical stage B, C: 20, D2: 82) patients were enrolled. QOL was assessed using the Functional Assessment of Cancer Therapy, General and Prostate (FACT-G/P). Disease-specific pain response was assessed using the visual analog scale and the face rating scale. In patients with stage D2 PC, mean age, serum prostate-specific antigen level, and performance status were 72.5 +/- 7.1 years (range, 55-88), 217 +/- 467 ng/mL (range, 0.1-2600), and 1.4 (0-4), respectively. The score of physical well-being and FACT-P was significantly lower in stage D2 patients, compared with those of stage B/C (P = 0.02, 0.0088, respectively). Performance status, extent of disease, and the visual analog scale were related with a poor QOL score (P = 0.0054, 0.01, <0.0001, respectively). Thirty-two patients (39%) had disease-specific pain, and 25 patients received a related treatment. Ten patients under morphine analgesics maintained better QOL in almost all domains, compared with the seven patients without any painkillers. Combined use of FACT and pain scales enhances the objective assessment of QOL and pain status in PC patients. Control of disease-associated pain is crucial to improving QOL in stage D2 PC patients.