Oral lesions were included in some of the first descriptions of the acquired immunodeficiency syndrome (AIDS), and it has become clear in the ensuing years that these lesions may represent some of the earliest signs of infection with the human immunodeficiency virus (HIV), may be of prognostic significance in the subsequent development of AIDS, and may, if not treated, produce significant morbidity. Understanding oral lesions may shed light on the other manifestations of HIV disease. Oral examination is an important part of any physical examination, and nowhere is this more important than in the case of suspected HIV infection.