Imiquimod is an immune response-modifying agent that demonstrates potent antiviral and antitumour activity. Although it's use has been approved by the FDA (Food and Drug Administration) in the treatment of external genital and perianal warts, actinic keratosis on the face or scalp and superficial basal cell carcinomas, it has recently been tried to treat different types of dermatological diseases including molluscum contagiosum, herpes simplex, melanoma, T-cell lymphoma. Side effects of imiquimod are erythema, itching, burning, crusting, and rarely cytokine-release syndrome, exacerbation of inflammatory skin conditions. In thi review, the structure of imiquimod, mechanism of action and its usage in the treatment of different skin diseases are discussed. © 2007 Bentham Science Publishers Ltd.