Tissue wasting often occurs during human immunodeficiency virus infection and acquired immune deficiency syndrome. While weight-loss in the human immunodeficiency virus-infected individual can be seen as an isolated symptom, catabolism during acquired immune deficiency syndrome is usually associated with complications such as diarrhea, malabsorption, fever and secondary infection. Glutamine is an amino acid central to many important metabolic pathways and recent findings suggest that glutamine depletion may explain the progression of tissue wasting during human immunodeficiency virus infection.