Economic studies of HIV/AIDS interventions are important for providing cost-effective care. This paper presents a costeffectiveness study of a three-arm clinical trial conducted at Tufts University School of Medicine/New England Medical Center in Boston, Massachusetts that treated 50 patients with AIDS wasting from March 1998 through January 2001. This study compared the costs and impacts of a nutritional counseling intervention alone (NC arm), the nutrition intervention with oxandrolone (OX arm), and the nutrition intervention with progressive resistance training (PRTarm) for the treatment of AIDS wasting. The cost of each intervention was derived for both the three-month clinical trial and a six-month estimated community model (ECM), its projected adaptation to community-based medical care. The cost determination involved obtaining and multiplying unit economic costs and quantities expended of each resource within each study arm. The ECM average cost per client in the cost-effectiveness analysis incorporated both institutional and societal perspectives. The costeffectiveness analysis compared the cost of each intervention to its quality-adjusted life-year (QALY) gain (Zeckhauser and Shepard, 1976). From a societal perspective, for the NC arm, the cost per client totaled US dollars 983 for the actual and US dollars 596 under the ECM. For the OX arm, the cost per client totaled US dollars 3,772 for the actual study and US dollars 3,385 under the ECM. For the PRT arm, the cost per client totaled US dollars 3,189 for the actual study and US dollars 2,987 under the ECM. Under the societal perspective the cost per QALY was US dollars 55,000 (range: US dollars 51,000 to US dollars 83,000) for the NC arm, US dollars 151,000 (range: US dollars 149,000 to US dollars 171,000) for the OX arm, and US dollars 65,000 (range: US dollars 44,000 to US dollars 104,000) for the PRTarm. When using only an institutional perspective, the cost per QALY was US dollars 45,000 (range: US dollars 42,000-US dollars 64,000) for the NC arm, US dollars 147,000 (range: US dollars 147,000 to US dollars 163,000) for the OX arm, and US dollars 31,000 (US dollars 21,000 to US dollars 44,000) for the PRTarm. This paper shows that cost and cost-effectiveness analyses can be adapted to a community setting by combining information from community practice and costs with data from a randomized trial. Compared to other AIDS treatments, such as highly active antiretroviral therapies, all three interventions were affordable, but their cost-effectiveness was intermediate. Oxandrolone was the least cost effective of the interventions, even compared to nutrition alone, as it included similar or somewhat greater costs for less of an increase in quality of life. PRT was the most cost-effective treatment for AIDS wasting, particularly from an institutional perspective. Third party payers should consider coverage of PRT.