We evaluated the contribution of diabetes mellitus to premature ischemic heart disease mortality among US race- and gender-specific groups in 1986. Among persons aged 45 to 64 years, we examined ischemic heart disease death rates (corrected for underreporting of diabetes on death certificates) by diabetes status and calculated the population attributable risk due to diabetes for each group. Diabetes increased the ischemic heart disease death rate by 9 to 10 times for women but by only 2 to 3 times for men. Racial differences in ischemic heart disease mortality attributable to diabetes were greater for women (Blacks = 39%; Whites = 27%) than for men (Blacks = 19%; Whites = 14%). These discrepancies in the contribution of diabetes to ischemic heart disease mortality warrant further study.