Summary We have examined smoking habits in 108 patients with psoriasis, including some with palmoplantar distribution, and compared the results with matched controls from the community. There was a significant association between psoriasis, current smoking status(OR=2.7, 95% CI 1.44-5.42, P<0.01) and smoking habits prior to the onset of disease(OR=3.75, 95% CI 1.68-9.47, P<0.001). There was also a marked dose-response relationship; the relative risk of psoriasis in those currently smoking more than 20 cigarettes/day was significantly elevated(OR=5.3, 95% CI 2.1–13.0, P<0.001). Separate analysis of patients without palmoplantar distribution of psoriasis showed a significant association with smoking prior to onset of psoriasis(OR=3.6, 95% CI 1.5–9.8, P<0.001). Smoking may play a role in the aetiology of this common skin disorder.