Oral lesions are common in HIV infection and may be the first sign of AIDS. This article reviews the oral fungal and viral infections commonly detected in HIV-infected patients, particularly candidiasis, deep fungal infections, herpes simplex virus infections, cytomegalovirus infections, and oral hairy leukoplakia. The neoplasms associated with AIDS such as oral Kaposi's sarcoma and lymphoma are related periodontal diseases. Each disorder is discussed by clinical appearance, diagnosis, and management. Recent advances in therapy are stressed.