Psoriasis is a chronic immune-mediated skin disease that affects 125 million people worldwide. Over the last two decades, biologic drugs have revolutionized the treatment of moderate to severe plaque psoriasis. They act on one or more molecular targets and thus modify or inhibit signal transduction pathways in the pathophysiological process of the disease. This articles summarizes cutaneous adverse effects to biologic drugs used in the treatment of psoriasis. Because they were on the market first, most of the literature covers cutaneous adverse effects of tumor necrosis factor-α (TNF-α) inhibitors, but increasingly more data are also available for adverse effects caused by newer biologics that inhibit the interleukin (IL)-12/23, IL-17, and IL-23 pathways. Some cutaneous adverse effects are general-for example, injection site reactions-whereas others are more class-specific; namely, Candida infections in IL-17 inhibitors. However, because some biologic drugs used in psoriatic patients are also registered for the treatment of certain other immune-mediated diseases such as rheumatoid arthritis, data regarding cutaneous adverse effects come from various sources that differ in quality and often cannot be interpreted without bias.