A 48-year-old Puerto Rican woman developed extensive ulcers on her buttocks, right arm, and thighs over a 3 1/2-year period, The lesions began as small, subcutaneous nodules which subsequently ulcerated and expanded up to 19 cm in diameter. Biopsy of both ulcerated and nonulcerated lesions showed acid-fast bacilli. Culture of both types of lesions grew Vibrio extorquens, a partially acid-fast methanolophilic organism not previously associated with disease in humans. The patient developed agglutinating antibody, titer 1:80, to this organism. The disease responded to treatment with antibiotics to which the organism was sensitive in vitro.