In 1984, 24 percent of the homicide victims in the United States were related to their assailants. About half were spouses. Family homicides increased in the 1960's and 1970's, but has declined in the 1980's. Most family murders take place after a long history of assaults. One national study estimated that 16 percent of marriages experience some kind of violence during the year. Children experience even higher rates of violence, both from their parents and from siblings. Little chance exists of expanding treatment services to serve all those affected by family violence. Public health efforts to prevent family violence should focus on a limited number of risk factors. Demonstration programs should be set up and carefully evaluated. Medical professionals should also contribute to secondary prevention efforts by developing diagnostic criteria to identify family assault cases and by reconceptualizing family violence as the major threat to health that it is. 38 references.