Objective. To investigate the mechanism of tazarotene in active psoriasis vulgaris. Methods. HB-EGF protein in active psoriatic lesions before and 10 days after the treatment of tazarotene was detected by immunohistochemistry. Results. There was nearly no expression of HB-EGF in psoriatic lesions (9.1%), but after the treatment by tazarotene, there was expression of HB-EGF not only in basal layer (95.5%), but also focal expression in suprabasal layers of epidermis (77.3%). Conclusion. Tazarotene inhibit proliferation and induce apoptosis of keratinocytes through upregulating expression of HB-EGF in psoriatic epidermis.