Treatment compliance is an important variable in drug use intervention. For pregnant drug-misusing women, compliance with treatment has been particularly problematic, even in specialized and more intensive treatment programs. The present study, conducted from March 1999 to June 2000, compared maternal/infant outcomes in pregnant drug-using women who were either compliant or noncompliant with drug use interventions offered through a prenatal care clinic. Compliant women (N = 11) completed four therapy sessions (behavioral reinforcement of drug abstinence + brief motivational therapy), while noncompliant women (N = 20) participated in zero to three therapy sessions. The two groups were similar on demographic and drug use severity measures. Compliant mothers, however, gave birth to infants with higher birthweights than noncompliant mothers. Over half of compliant mothers were also drug-free at delivery, compared to one-fourth of noncompliant mothers. These data support an association between treatment compliance and birth outcomes, and highlight the need to develop strategies for improving compliance with such interventions.