A 72-year-old woman with a long history of recalcitrant psoriasis developed severe generalized erosions after receiving low-dose (7.5 mg) methotrexate. Her clinical picture was consistent with toxic epidermal necrolysis and showed a gradual response to systemic steroids and topical therapy. Patients with underlying dermatoses or previous cutaneous insults may be particularly prone to adverse cutaneous reactions resulting from folic acid antagonists.