In this National Institute of Justice-funded study, random digit dialing telephone survey methodology was used to screen a large, nationally representative sample (N = 12,500) of the noninstitutionalized U.S. adult population to identify surviving family members and friends of victims of criminal homicide and alcohol-related vehicular homicide. A total of 9.3% of the national sample had lost a family member or friend to homicide. Immediate family survivors (n = 206) completed an interview assessing demographic characteristics and DSM-III-R criteria for homicide-related post-traumatic stress disorder (PTSD). The interview participation rate was 84%. Among immediate family survivors, 23.3% developed PTSD at some point in their lifetimes, and 4.8% met full diagnostic criteria for PTSD during the preceding 6 months. Survivors of criminal and vehicular homicide victims were equally likely to develop PTSD. Survivors who experienced the homicide during their childhood, adolescence, or adulthood also showed equal likelihood of PTSD. Clinical implications of findings are discussed.