The natural form of vitamin D-3, 1,25-dihydroxyvitamin D-3, modulates epidermal proliferation and differentiation and inhibits immune induction. Calcipotriol (calcipotriene) is a synthetic vitamin D analogue that partially separates the newly identified effects from the classic hypercalcemic effect. Topical treatment with calcipotriene has been shown to be effective, well tolerated, and safe for psoriasis.