Unrelieved pain is a major factor that influences suicide risk among terminally ill patients, but little is known about the relationship between pain and the risk of completed suicide in the general population. We prospectively examined the association between self-reports of pain and subsequent risk of completed suicide in 26,481 men aged 40 to 79 years from the Ohsaki National Health Insurance Cohort study, a population-based, prospective cohort study initiated in 1994. On the basis of a five-item questionnaire on pain, individuals were classified as having no pain, very mild pain, mild pain, or moderate or severe pain. Completed suicide cases were documented from 1995 to 2001. During 131,027 person-years, 64 completed suicides were documented. After adjustment for covariates, the risk for completed suicide was significantly higher in the subjects with more pain. Multivariate hazard ratios (95% confidence intervals) relative to the subjects who had no pain were 1.36 (0.67-2.75), 2.11 (1.02-4.33), and 2.93 (1.34-6.42) in the subjects who had very mild pain, mild pain, and moderate or severe pain, respectively (P for trend=0.004). Stratified analysis showed that the positive association between pain and suicide risk was robust in the subjects with good health, low stress, adequate sleep, good physical activity, and no history of chronic diseases. Our results suggest that pain is associated with an increased risk of completed suicide among Japanese men. The association was consistently observed among apparently healthy subjects.