Background: Intimate Partner Violence (IPV) is a major public health problem with serious consequences. This study was conducted to assess the magnitude of IPV in Southwest Ethiopia in predominantly rural community. Methods: This community based cross-sectional study was conducted in May, 2009 in Southwest Ethiopia using the World Health Organization core questionnaire to measure violence against women. Trained data collectors interviewed 851 ever-married women. Stata version 10.1 software and SPSS version 12.0.1 for windows were used for data analysis. Result: In this study the life time prevalence of sexual or physical partner violence, or both was 64.7% (95%CI: 61.4%–67.9%). The lifetime sexual violence [50.1% (95% CI: 46.7%–53.4%)] was considerably more prevalent than physical violence [41.1% (95%:37.8–44.5)]. A sizable proportion [41.5%(95%CI: 38.2%–44.8%)] of women reported physical or sexual violence, or both, in the past year. Men who were controlling were more likely to be violent against their partner. Conclusion: Physical and sexual violence is common among ever-married women in Southwest Ethiopia. Interventions targeting controlling men might help in reducing IPV. Further prospective longitudinal studies among ever-married women are important to identify predictors and to study the dynamics of violence over time.