Its relative impact on premature mortality, as measured by the percentage of years of potential life lost (YPLL) before age 65 from all causes of death due to homicide, has nearly doubled (93 percent increase). This increase calls attention to the emerging importance of interpersonal violence relative to all public health problems affecting persons under 65 years of age. The percentage of YPLL from all causes of death due to homicide increased in each race/sex group and for both firearm and nonfirearm means of homicide. The increase in homicide YPLL was traced mainly to an increase in the number of homicide deaths and, to a small extent, to a decrease in the average age at death of homicide victims. 3 figures, 1 appendix, 10 references. (Author abstract)