Patients with severe immunosuppression as a consequence of infection by human immunodeficiency virus (HIV) are at risk for a number of severe periodontal diseases. HIV-associated gingivitis and HIV-associated periodontitis (HIV-P) are seen exclusively in HIV-infected persons. In some cases HIV-P may extend into adjacent soft tissue and bone, resulting in necrotizing stomatitis of periodontal origin. In addition, acute necrotizing ulcerative gingivitis has also been reported to have an increased prevalence in HIV-infected patients. The clinical and microbiologic features of HIV-associated gingivitis and HIV-P suggest that these diseases are early and later stages of the same lesion, that results in severe gingival erythema, extensive soft tissue necrosis, and destruction of alveolar bone. Although acute necrotizing gingivitis and the initial stages of HIV-P share a number of clinical signs current evidence indicates that they are distinct pathologic processes. Treatment of these lesions requires debridement, local antimicrobial therapy, immediate follow-up care, and long-term maintenance. In addition, patients with systemic involvement or extensive and rapidly progressing lesions may require systemic antibiotics appropriate to the organisms that dominate the lesion.