One hundred and sixty-five patients with acne completed a questionnaire on smoking habits. Amongst 96 males, 19.7% were smokers (95% confidence interval 12.4-29.2%) compared to an expected prevalence of 34.5% from national statistics (P < 0.001). For 69 females, a prevalence of 12.1% (95% confidence interval 6.1-23.3%) was obtained compared to 32.7% expected (P < 0.001). The findings of this study support the hypothesis that some component of cigarette smoke, possibly nicotine, has an anti-inflammatory action on acne.