A total of 161 heroin and speedball users in San Antonio, Tex., were interviewed between 1989 and 1992. Users were classified according to whether or not they had even been on methadone maintenance. Opioid users who had never been on methadone maintenance were more likely to express a negative attitude toward methadone maintenance than users who had been on it (50 percent versus 30 percent). Sources of negative attitudes fell into the following categories: general societal disapproval of addictive drugs, including methadone; prior experience with 12-step groups or abstinence-based treatment programs; previous forced rapid detoxification from methadone in jail; and observation of methadone-maintained peers who continued to use drugs. Very few respondents reported adverse effects from methadone itself as a source of negative attitudes. Sources of positive attitudes included prior successful treatment with methadone and observation of methadone patients who stopped using drugs. 4 tables and 22 references