This study provides estimates of the economic cost of intimate partner violence perpetrated against women in the US, including expenditures for medical care and mental health services, and lost productivity from injury and premature death. The analysis uses national survey data, including the National Violence Against Women Survey and the Medical Expenditure Panel Survey, to estimate costs for 1995. Intimate partner violence against women cost $5.8 billion dollars (95% confidence interval: $3.9 to $7.7 billion) in 1995, including $320 million ($136 to $503 million) for rapes, $4.2 billion ($2.4 to $6.1 billion) for physical assault, $342 million ($235 to $449 million) for stalking, and $893 million ($840 to $946 million) for murders. Updated to 2003 dollars, costs would total over $8.3 billion. Intimate partner violence is costly in the US. The potential savings from efforts to reduce this violence are substantial. More comprehensive data are needed to refine cost estimates and monitor costs over time.