Interviews were conducted with 408 heroin users and 150 cocaine users as part of the Drug Transitions Study. Subjects were found by a team of specially recruited and trained Privileged Access Interviewers who had existing contacts or could easily develop contacts with drug users and were nonthreatening to the study group. Data were collected using a structured interview lasting approximately 45 minutes. Findings revealed that women were younger than men and that differences existed in male and female drug use patterns. Women used smaller amounts and for a shorter duration and were less likely to inject than their male counterparts. No differences were observed between treatment contact for heroin users but differences were found among the cocaine-using sample, with men being more likely to have contacted a treatment agency. Men financed themselves through more criminal activities than women. Drug-using sexual partners exerted an important influence over women's drug use, with most female injectors having been given their first injection by a male sexual partner. The authors conclude that structural differences in drug use patterns among female drug users and the influence of male sexual partners are likely to play an important role in identifying appropriate treatment options for female drug drug users. 29 references and 3 tables