Calcipotriol (Dovonex) ointment has been shown to be an effective, well tolerated, and acceptable treatment for psoriasis vulgaris in adults. This open study was conducted in 16 U.K. centres to assess the safety and efficacy of calcipotriol ointment in treating psoriasis vulgaris in children. Following a 2-week washout, patients were treated with calcipotriol ointment, 50 micrograms/g twice daily, for up to 8 weeks. A blood sample was taken on entry and a second 'on treatment' sample was taken after either 2 or 8 weeks treatment. Sixty-six children (26 boys, 40 girls, age range from 3 to 14 years) entered and 58 completed the study. There was a statistically significant reduction in the mean (+/- SD) Psoriasis Area and Severity Index (PASI) from 6.1 +/- 3.5 at the start of treatment to 2.7 +/- 1.9 at the end of treatment (P < 0.001). Marked improvement or clearance of psoriasis at the end of treatment occurred in 65% of patients as assessed by the investigator and 62% as assessed by the patient. Cosmetic acceptability of calcipotriol ointment was found to be good or excellent in 79% of patients. Eight patients withdrew from the study (four defaulted, two unacceptable responses, two adverse events). Adverse events were reported by 16 patients: the most common being local irritation (seven patients). There was no significant change in the mean serum ionized calcium from baseline to 2 or 8 weeks treatment. Similarly, there were no consistent or clinically important changes in haematological, or other biochemical parameters, measured during the study period. Calcipotriol ointment has been shown to be an effective, well tolerated, and acceptable treatment for psoriasis vulgaris in children.