Three patients are described, each of whom had an inflammatory pyoderma involving predominantly the face, neck, and upper truncal region. Marked destruction of tissue eventually occurred. Repeated studies failed to establish a specific bacteriologic or mycotic cause. Histopathologic studies revealed ulcer formation but no evidence of primary vasculitis. The reactions were unresponsive to systemic antibiotic therapy; adrenocorticosteroid therapy seemed necessary to arrest the process in each patient. Differential diagnosis included, among other possibilities, pyoderma gangrenosum, hemolytic streptococcic gangrene, synergistic gangrene, pyoderma chancriforme faciei, lethal midline granuloma, Wegener's granulomatosis, necrotizing vasculitis, and a hyperreactivity state. One patient recovered with no recurrence of the disease to date; the second requires daily adrenocorticosteroid therapy to suppress his skin reaction; the third patient died with no apparent evidence of other disease at autopsy.