AbstractSevere unrelenting weight loss appears to be a major component of the clinical picture seen in the patients with Acquired Immune Deficiency Syndrome (AIDS). Weight loss has been associated with a poor prognosis for AIDS patients with Kaposi's sarcoma. Strong evidence from a variety of clinical situations indicates that malnutrition per se adversely affects the cellular immune system and the susceptibility of individuals to infectious problems. In addition, weight loss of the degree commonly seen in the AIDS population places patients at risk of death because of resultant organ dysfunction. Moreover, severe weight loss may preclude recovery from infectious complications that otherwise would not represent a lethal challenge to the host. Because even appropriately directed therapies may not be successful when used in patients with severe weight loss, it is crucial to identify the mechanism of the weight loss associated with AIDS and to rapidly initiate evaluation of agents capable of altering or reversing this potentially lethal complication.