A clinical and epidemiological study of psoriasis in Sri-Lanka is presented. The prevalence in the population is estimated to be over 0.4%. The clinic incidence was 8.7%; of these 53.2% were male, and 46.8% female and 8.3% reported a family history of the disease. The mean age at onset was 25.2 years. The frequency distribution for the age at onset was bimodal with peaks at the second and fifth decades. The age at onset was significantly low in females, in patients with a family history of the disease, in those affected by weather changes and in patients whose disease was precipitated by sore throats. The existence of natural subpopulations of patients is suggested. Clinical types and complications of the disease were not essentially different from those observed in the West.