BACKGROUND: Topical corticosteroids are known to impair the epidermal barrier, even after short-term use, whereas topical vitamin D analogues can have a reparative effect. Combination products using corticosteroids and vitamin D analogues have gained popularity in recent years and may provide a means to minimize skin atrophy in patients treated with topical corticosteroids. OBJECTIVE: To compare epidermal barrier function and cutaneous atrophy after 4 weeks of calcipotriene 0.005% and betamethasone dipropionate 0.064% topical suspension (Taclonex® TS) versus betamethasone dipropionate 0.05% lotion (Diprosone®). METHODS: Ten subjects with moderate plaque psoriasis were enrolled. Patients were randomized to apply calcipotriene 0.005%/betamethasone dipropionate 0.064% once daily to psoriasis plaques on one side of the body and betamethasone dipropionate 0.05% lotion twice daily to plaques on the other side. Biopsies were performed at baseline and after four weeks of treatment to evaluate for epidermal and dermal changes. RESULTS: Treatment with betamethasone lotion resulted in significant decreases in epidermal thickness and dermal thickness. In contrast, treatment with calcipotriene/betamethasone did not lead to significant decreases in epidermal thickness or dermal thickness. Comparing betamethasone and calcipotriene/betamethasone, there was a significantly greater reduction in epidermal thickness with betamethasone lotion versus calcipotriene/betamethasone (P less than .0001). Relative differences in dermal thickness and transepidermal water loss (TEWL) did not reach statistical significance. CONCLUSION: This study is the first to demonstrate that treatment of plaque psoriasis with a combination topical corticosteriod and calcipotriene product results in greater preservation of the skin layers relative to topical corticosteroid use alone. These results hold important ramifications for minimizing cutaneous atrophy in patients receiving treatment with topical corticosteroid .