Both the incidence of and mortality from bleeding and perforated peptic ulcers are increasing. We assessed the association between smoking, intake of alcohol (including type of alcoholic beverage), and risk of a complicated peptic ulcer in a population-based study of 26,518 Danish subjects followed up for an average of 13.4 years. There were 214 cases of incident bleeding and 107 cases with perforated ulcers. We estimated relative risks (RRs) for incident bleeding and perforated peptic ulcers using Poisson regression analysis. Smoking more than 15 cigarettes per day compared with never smoking increased the risk of a perforated ulcer more than threefold [RR = 3.5; 95% confidence interval (CI) = 1.7-7.1)]. Drinking more than 42 drinks per week increased the risk of a bleeding ulcer fourfold (RR = 4.4; 95% CI = 2.3-8.3) compared with drinking less than one drink per week. Using the same comparison group, subjects who drank more than 21 drinks per week but no wine were at a higher risk of a bleeding ulcer (RR = 8.8; 95% CI = 2.2-35) than drinkers of the same amount of alcohol, but with more than 25% of their intake as wine (RR = 2.4; 95% CI = 1.0-6.0).