Intimate partner violence (IPV) has been recognized as a risk factor for HIV and sexually transmitted infections (STIs) among women, particularly among those who are drug involved. This study examines the temporal relationships between sexual and/or physical partner violence (IPV) and sexual risk of HIV/STI transmission in a longitudinal study with a random sample of 416 women enrolled in methadone maintenance treatment programs in New York City. Two hypotheses are tested: whether sexual risk-related factors or risk reduction behavior leads to subsequent IPV (H1); and whether IPV decreases likelihood of subsequent risk reduction behavior (i.e., requesting to use condoms) or increases likelihood of certain sexual risk-related factors (i.e., inconsistent condom use, having unprotected anal sex, having more than one partner, exchanging sex for drugs or money, having had an STI, being HIV positive, having a partner who engaged in HIV risk) (H2). Participants were interviewed at three waves: baseline, six months and twelve months. Hypotheses were examined using propensity score matching and multiple logistic regression analyses. The prevalence rate of any physical or sexual IPV was 46% at baseline. Findings for H1 indicate that women who reported always using condoms at wave 2 were significantly less likely than women who reported inconsistent or no condom use to experience subsequent IPV at wave 3. Similarly, increased risk of IPV at wave 3 was associated with self-reported STIs (OR=2.0, p=.03), and unprotected anal sex (OR= 2.0, p<.01); always requesting that partners use condoms was associated with a significant decrease in subsequent IPV (OR=.18, p<.01). Findings for H2 suggest that IPV at wave 2 decreased the subsequent likelihood of always using condoms at wave 3 (OR=.41, p<.01) and always requesting that a partner use condoms (OR=.42, p=.02). The implications of the findings for HIV prevention interventions for women on methadone are discussed.