Oral candidiasis (OC) is a frequent oral manifestation of HIV infection, is a marker disease and occurs as a pseudomembranous, erythematous or rarely hyperplastic variant; angular cheilitis is also seen. Candida albicans is frequently isolated but other species such as C. krusei and C. dublienensis are emerging. Resistance against fluconazole is common. Bacterial oral infections are comparatively rare and are predominantly localized to the gingiva and periodontium. Linear gingival erythema, necrotizing ulcerative gingivitis and necrotizing ulcerative periodontitis have been described in HIV-infected patients. Initially, these diseases were considered specific for HIV infection. In recent years, however, it has become apparent that gingivitis and periodontitis in HIV-infected patients do not differ from those in immunocompetent individuals. AIDS-associated Kaposi's sarcoma (KS) predominantly occurs at the palate, the gingiva and the dorsum of the tongue. Histopathologically, oral KS is identical to classical KS. Oral KS has been treated surgically, using laser, radiotherapy and intralesional injections with chemo- and immunotherapy. After introduction of highly active antiretroviral therapy (HAART) oral manifestations, such as OC, gingivo-periodontitis and KS are rarely seen.