To display the extent of variations in mortality according to geographic regions in New York City, we have compared mortality in New York City as a whole with that of the South Bronx. Mortality records for 1988 to 1992 and 1990 US census data for New York City were linked. The 471,000 residents of the South Bronx were younger, less educated, and more likely to lack health insurance than other New Yorkers. Using age- and gender-stratified populations and mortality in New York City as standards, age-adjusted death rates and excess mortality in the South Bronx were determined. All-cause mortality in the South Bronx was 26% higher than the city as a whole. Mortality for AIDS, injury and poisoning, drug and alcohol abuse, and cardiovascular diseases were 50% to 100% higher in the South Bronx than in New York City; years of potential life lost before age 65 in the South Bronx were 41.6% and 44.2% higher for men and women, respectively, than in New York City; AIDS accounted for the largest single share of excess premature deaths (21.8%). In summary, inequalities in health status, reflected by higher mortality rates in the South Bronx, are consistent with, and perhaps caused by, lower socioeconomic status and deficient medical care among residents of this inner-city community.