Alcohol consumption and cigarette smoking were evaluated in relation to development of benign prostatic hyperplasia (BPH) among 29,386 members of the Health Professionals Follow-up Study. Men who were 40-75 years old in 1986 and free of prior BPH surgery, diagnosed cancer at baseline, and prostate cancer at baseline and during follow-up were followed for incidence of BPH surgery from 1986 to 1994. Cases were men who reported BPH surgery between 1986 and 1994 (n = 1,813) or who scored > or = 15 points of 35 on seven lower urinary tract symptom questions modified from the American Urological Association symptom index in 1992 and 1994 (n = 1,786); noncases were men who scored < or = 7 points (n = 20,840). After controlling for age, race/ethnicity, body mass index, physical activity, and mutually for alcohol intake and smoking, moderate alcohol consumption was inversely related with total BPH (30.1-50 g/day vs. 0: odds ratio (OR) = 0.59, 95% confidence interval (CI) 0.51-0.70; p trend < 0.0001), although the relation was attenuated at high intake (> or = 50.1 g/day vs. 0: OR = 0.72, 95% CI 0.57-0.90). Current cigarette smoking was positively related to total BPH only among those who smoked 35 or more cigarettes/day (compared with never smokers: OR = 1.45, 95% CI 1.07-1.97). These findings suggest that moderate alcohol consumption and avoidance of smoking may benefit BPH.