Interviews were previously conducted with 72 heroin-addicted female street prostitutes who spread HIV by sharing injection paraphernalia and engaging in unprotected sex with multiple male customers. Most were willing to enroll in free methadone maintenance if made available. Forty-one female addict-prostitutes subsequently entered free methadone maintenance. Twenty-five remained in treatment after one year. Their personal income from prostitution and other crime was reduced 58%; income from legal sources increased 86%. Total urinalyses positive for non-prescribed drugs decreased from 80% on admission to 51%. This pilot study validates the attraction of free methadone maintenance and concomitant reduction of illegal drug use and prostitution, two predictors of HIV infection. However, close supervision and effective counseling and rehabilitative services provided by better trained staff are required for successful outcomes among addict-prostitutes in methadone maintenance.