To determine the risk of cutaneous neoplasia following photochemotherapy (PUVA), we reviewed patients with psoriasis treated at our unit between 1979 and 1991. Two hundred and forty-five patients were assessed, with a median duration of follow-up of 9.5 years. Fifty-nine per cent were male, and 41% female. The median number of exposures was 59, and the median total dose was 133 J/cm2 for the group as a whole. Non-melanoma skin cancers (NMSC) occurred in six individuals (2.4%). Basal cell carcinoma occurred in all six and one individual also developed four squamous cell carcinomas and Bowen's disease of the penis. No cases of malignant melanoma were recorded. Patients who developed NMSC received a median number of 225 exposures and a median cumulative dose of 654 J/cm2. Compared with a control study population in West Glamorgan, Wales, there was a 1.4 (95% confidence limits (CL) 0.5 and 3.1) times increased risk of NMSC. A statistically significant increased incidence of NMSC was found for patients who had received 100 or more exposures, and 250 or more J/cm2, with risks of 3.7 (95% CL 1.0 and 9.5), and 4.0 (95% CL 1.1 and 10), respectively. A PUVA dose of < 250 J/cm2 or < 100 exposures conferred a minimal increase in risk of NMSC in our study population.