In traditional public health terms, primary prevention entails lowering the number of new cases by changing behavior or environmental factors. One way for physicians to address environmental factors is to recognize ways in which the medical profession may be helping perpetuate a harmful environment. Further changes to the structure of medical practice are needed if the environment surrounding domestic violence is to be altered. The status structure of medicine, its traditional male bias, and the strict hierarchical organization of medical training all have been identified as barriers to physicians' participation in domestic violence intervention efforts. Primary prevention efforts must address both the substance of physician norms and their organizational context. Secondary prevention extends beyond identification of domestic violence to include appropriate early intervention. To date, specific elements of intervention generally include identification, validation, treatment of medical needs, assessment of mental health needs, clear documentation, safety assessment, and referral to law enforcement and community-based domestic violence services. Limited by the relative paucity of clinical experience with victims of domestic violence, current secondary-prevention medical protocols must be updated, based on ongoing evaluation in clinical settings. Tertiary prevention involves the treatment of victims of domestic violence so that the abuse will not be repeated. Tertiary prevention of domestic violence will require health care organizations to incorporate and invest in crisis intervention, emergency hospitalization for shelter, counseling, support groups, and advocacy, rather than simple identification and referral. Such a comprehensive approach will require changes in medical practice that rival those seen in law and law enforcement practice.