In a prospective cohort study of 46,755 men free of cancer enrolled in the Health Professionals Follow-up Study, participants reported their height, weight, diet, & physical activity on repeated occasions from 1986 through February 2002. A total of 131 men died by suicide during follow-up. A higher body mass index was related to a graded decline in the suicide mortality rate. Risk of death from suicide was strongly inversely related to body mass index but not to height or to physical activity. Further research into mechanisms of lower risk among overweight & obese men may provide insights into effective methods of suicide prevention. (65 refs.)