The HIV infection rate is increasing among women in general and for female inmates specifically (Maruschak 2004), which makes understanding the correlates of risky sexual behaviors critical for this population. Partner relationships, particularly the extent to which women perceive they have power within the relationship, may be important in modeling risk behaviors. Few studies have considered the association between relationship power and HIV risk behaviors among women offenders. This study examines women's perceptions of their relationships using the Sexual Relationship Power Scale (Pulerwitz, Gortmaker, & DeJong 2000) and NIDA's HIV Risk Behavior Assessment (NIDA 1995). Data were collected from female inmates in four prisons as part of the Reducing Risky Relationships for HIV protocol being conducted through the NIDA's Criminal Justice Drug Abuse Treatment Studies (CJ-DATS) cooperative agreement. Women reported whether they had engaged in five types of unprotected sex in the month prior to incarceration. Logistic regression models of the associations between relationship power and five types of unprotected sex revealed some support for the importance of power as a protective factor in reducing the odds of unprotected sexual behaviors. Implications and findings are presented to add to understanding of partner relationships and HIV risk behaviors.