30 patients were treated with daily application of calcitriol (1 alpha, 25-dihydroxyvitamin D3) ointment 15 micrograms/g in white petrolatum. The patients were divided into three groups according to the size of their total area of psoriasis. They were treated for 6 weeks, and investigated first with weekly and then with two-weekly estimations of calcium metabolism (serum calcium, 24-hour urinary calcium, parathyroid hormone, 25-hydroxyvitamin D3 and calcitriol). Ninety percent of the patients cleared or improved and there were no significant side effects or local intolerance. Cosmetic acceptance was good. No clinically significant changes in calcium metabolism were observed in spite of calcitriol application ranging between 73.98 and 306.10 micrograms daily (normal daily synthesis being 1-2 micrograms).