Surveillance reports describe an increase in asthma prevalence, and cite New York City as an area of excessive asthma mortality. To assess trends and the influence of geography, race, and ethnicity on hospital admission rates for asthma between 1989 and 1991, data of all admissions for asthma to New York City hospitals were reviewed. The average citywide annual hospital admission rate was 681 per 100,000 population, and the racial and ethnic distribution was 1,003 per 100,000 Hispanic patients, 810 per 100,000 for blacks, and 242 per 100,000 for whites (p < 0.0001). Bronx and Manhattan had the highest admissions rates, and contained a few zip codes with very high rates. In these zip codes, admission rates were consistently highest among Hispanics, followed by blacks and whites. New York City asthma admission rates increased 12.7 percent during the study. Very high admission rates among Hispanic patients and high rates in blacks, in specific geographic areas, are responsible for this trend. Targeted education and treatment programs could reduce hospital admissions and mortality in small geographic areas with high asthma morbidity.