This report describes a case of HIV-associated periodontitis complicated by necrotizing stomatitis in a homosexual male patient with AIDS. Necrotizing stomatitis is a rapidly progressive ulcerative and necrotic infection that causes massive destruction of the oral tissues and underlying bone. Like HIV periodontitis, it appears to be related to the immune suppression caused by human immunodeficiency virus (HIV) infection; importantly, it may be life threatening. In this case, initial resolution resulted from local debridement in association with metronidazole therapy. Long-term clinical management consisted of monthly professional prophylaxis, good oral hygiene, and daily rinses with chlorhexidine. This case suggests that progressive oral necrotizing infection should be recognized as one element in the spectrum of oral manifestations of HIV infection.