Opiate users seeking treatment during similar time periods in 1986 (n = 60) and 1988 (n = 82) did not differ significantly with regard to demographic factors, length of addiction, use of cocaine, history of alcohol problems, or indices of depression. In 1988, however, users reported significantly lower rates of current intravenous drug use than was reported in 1986: 39% in 1988, compared to 14% in 1986, reported not currently using IV (chi 2(1, N = 142) = 11.302, p < .001). For the combined periods, current IV users (n = 102) did not differ significantly from those who were not currently using IV (n = 40) with regard to demographic factors, size of habit, history of alcohol problems, or indices of depression. Current IV users had used opiates longer (mean 11.3 years versus 8.4 years; t(1, 65) = 2.20, p < .03), and there was a trend for cocaine use to be associated with current IV administration. For the smaller subset of those who survived waiting lists of between 1 to 4 months from the time of intake to program admission and physical examination (n = 81), 35% (6/17) of those who were not IV drug users at the time of clinic intake reported resuming or initiating IV drug use by the time of program admission. The validity of self-reports of not using IV at the time of program admission was assessed by comparison of self-report with findings of track marks on physical examination: inconsistencies were detected in 11% (1/9) of those whose self-reports indicated no current IV use.