A patient with progressive bullous pemphigoid developed an occult lung abscess while being treated with high dosage corticosteroids. The lung abscess was successfully treated with long-term, high dosage, intravenously administered penicillin. Resistance to infection while receiving steroid therapy is discussed, and lung abscess as a complication of steroid therapy is reviewed. The insidious appearance of this unusual, but often fatal complication, in a patient with bullous pemphigoid, successfully treated, with concomitant resolution of the pemphigoid, prompted this case report.