Fourteen patients with 26 keratoacanthomas (KA) were treated weekly with intralesional injections of fluorouracil. Twenty-five lesions cleared in an average of three weeks (range, two to eight weeks) after an average of 2.8 injections. One KA failed to respond after five weekly injections and was excised. No recurrences or meaningful side effects were observed. It appears that treatment of KA with intralesional fluorouracil injections is a safe, effective, and convenient mode ot treatment yielding excellent cosmetic results.