Methotrexate has been associated with the development of skin ulceration in small numbers of patients with psoriasis. We describe a 58-year-old man with a 15-year history of plaque-type psoriasis. He had been treated with methotrexate therapy (15 mg orally per week for 32 weeks) and had ulcers develop within psoriatic plaques on both elbows, on the mucosal aspect of the lower lip, and in an appendectomy scar on the right lower quadrant of the abdomen. Ulcers healed upon discontinuation of methotrexate, but the scar eroded again upon reintroduction of methotrexate.