BACKGROUND: The biologically active form of vitamin D3, calcitriol, is effective in the treatment of psoriasis but can alter calcium metabolism. Calcipotriene is an analog of calcitriol that has low calcemic activity and aids in clearing psoriasis. OBJECTIVE: The purpose of this study was to determine the safety of topical therapy with calcipotriene particularly in relation to calcium and bone metabolism. METHODS: In a double-blind, randomized, parallel, vehicle-controlled trial, 78 adults with plaque psoriasis were treated twice daily with topical calcipotriene ointment (50 microgram/gm, maximum usage, 120 gm per week) or vehicle for 8 weeks. After a screening visit, patients were admitted to the hospital at weeks 0 (baseline), 1,2,4, and 8. Blood and urine chemistry analysis included parathyroid hormone, serum calcium, bone-specific alkaline phosphatase, urinary hydroxyproline, and 24 hour urinary calcium excretion. Bone densitometry measures were performed at baseline and week 8. RESULTS: No incidences of calcipotriene treatment-related hypercalcemia, calcium mobilization from bone, or clinically significant changes in bone density wer noted during this study. CONCLUSION: Topical application of up to 120 gm per week of calcipotriene ointment for 8 weeks is safe and effective for plaque psoriasis. There were no adverse effects on calcium and bone metabolism during this 8 week study.