We performed a cross-sectional study that included 100 HIV-infected Japanese men without hemophilia to examine the influence of smoking on HIV infection. History of smoking was obtained using a questionnaire. The percentage of current smokers was 40 % and was the highest (50 %) among men in their forties. The mean Brinkman index (BI, number of cigarettes smoked per day multiplied by years of smoking) was 450. The percentage of patients with a BI ≥600 was significantly higher in patients with an AIDS-defining event than in those without an AIDS-defining event. A BI ≥600 was associated with an AIDS-defining event. Reducing smoking appears to be critical to enhancing disease management efforts in Japanese men with HIV.