Background: Topical corticosteroids, commonly used for psoriasis, show diminished response on continuous use. Objective: We tested efficacy of topical corticosteroid and calcipotriene used on alternate weeks versus daily corticosteroid in patients with psoriasis. Methods: In a randomized, observer-blind design, the experimental group of 25 patients with stable plaque psoriasis received augmented betamethasone dipropionate 0.05% cream once daily in the first and third weeks and calcipotriene 0.005% ointment twice daily in the second and fourth weeks. The control group of 27 patients received augmented betamethasone once daily for 4 weeks. Results: The experimental regimen was more effective than the control regimen as evidenced by (1) more patients with at least a 90% reduction in Psoriasis Area and Severity Index (PASI) score (difference 49.5%, 95% confidence interval [CI], 26.1%-72.9%, P <.001), (2) lower PASI after 2 weeks (P ≤.04), and (3) greater percentage reduction in PASI after 2 and 4 weeks (difference 23.1% [CI, 11.1%-35.1%] and 46.4% [28.9%-63.8%], respectively; P <.001). The study had power of 93.7%. No patient had skin irritation. Conclusion: Use of augmented betamethasone and calcipotriene on alternate weeks is more effective than daily corticosteroid and represents a novel strategy for treating psoriasis. (J Am Acad Dermatol 2000;43:61-5.)