To improve detection of domestic violence as a problem for women seeking primary care, we compared the addition of a single question about domestic violence on an existing self-administered health history form, to discretionary inquiry alone. We studied 689 consecutive new women patients in an internal medicine practice. Domestic violence identification rose from 0% in the control group with discretionary inquiry alone to 11.6% (95% confidence interval 8.8-14.4%) when the health history form included the following question: "At any time has a partner ever hit you, kicked you, or otherwise physically hurt you?" The addition of a single question can increase identification of domestic violence as a problem in patients' lives.