The vitamin-D analogue calcipotriol has immunological properties which suggest that it may be effective in alopecia areata. To investigate this we assessed the response to treatment with this compound in a group of 20 patients with alopecia totalis or universalis. The study was of placebo-controlled double-blind design. Each subject applied ointment containing 50μg/g calcipotriol to one side of the scalp and matching vehicle to the other. There was no evidence of a response to calcipotriol in this group of subjects with very severe alopecia.