We studied the occurrence of ulcerative keratitis in five eyes of four patients who were examined at the University of Maryland Hospital ophthalmology clinic over a 12-month period. All were young women who were intravenous drug abusers, with no known predisposing factors for ulcerative keratitis. Two patients had acquired immunodeficiency syndrome (AIDS), one was human immunodeficiency virus (HIV)-positive, and the fourth refused HIV testing. One had a corneoscleral limbus to corneoscleral limbus keratitis; three had inferiorly located corneal ulcers (bilateral in one patient with AIDS). Corneal cultures disclosed Capnocytophaga species in the corneoscleral limbus to corneoscleral limbus keratitis. The remaining ulcers were polymicrobial; cultures of three grew Candida albicans, cultures of two grew alpha-hemolytic streptococci, cultures of two grew Staphylococcus aureus, and culture of one grew Pseudomonas aeruginosa. Treatment with topical fortified antibiotics and antifungal agents resulted in complete healing in all four inferiorly located ulcers. The corneal ulcer became perforated and the eye was eviscerated. Histopathologic analysis of the eviscerated specimen disclosed acute keratitis with necrosis and no microorganisms.