Detection of current (past 30 days) drug use by analysis of hair was examined along with self-reports of current use in a 1994 treatment needs assessment survey; the sample was 179 homeless/transient adults in New York state. Results of radioimmunoassay of hair (RIAH) were used to evaluate the veracity of self-reports of current cocaine use. Only 26% of those persons whose hair tested positive for cocaine (n=115) admitted to having used cocaine in the past 30 days. Subjects eligible for treatment, as indicated by a DSM-III-R diagnosis of cocaine dependency, were nearly four times as likely to admit current cocaine use than those who were not dependent. These results are consistent with other studies of populations at high risk for substance use.