The small intestine is a common site of involvement in patients infected with the human immunodeficiency virus (HIV). Although there are numerous mechanisms by which small intestinal disease may occur in HIV infected patients, the resulting clinical manifestations of these disorders are remarkably similar and include the development of diarrhoea, weight loss and nutrient deficiencies. In fact, the original designation of AIDS in African countries as the 'slim disease' underlines the importance of small intestinal involvement (most likely secondary to parasitic infections) which commonly occurs in Third World Countries. The current review will provide a clinically oriented overview of small intestinal disease in patients infected with HIV. Because specific data on treatment of small intestinal diseases in AIDS is often lacking, some presented information is based on the author's experience and opinions.