Morbidity and mortality due to asthma continues to increase despite advances in understanding the pathophysiology and treatment of the disease. We evaluated the potential risk factors for asthma morbidity and mortality in a large metropolitan city (St. Louis, MO) using small area geographic analysis. We found that the risk of hospitalization for children with asthma was 8.4 times greater (95% confidence interval [CI] 7.0-9.9) in lower socioeconomic zip code areas and 5.3 times greater (95% CI 4.7-5.9) in those zip codes with a higher percentage of African Americans. Similarly, the risk of death due to asthma was 6.4 times greater in the lower socioeconomic zip code areas (95% CI3.4-12.1). Lower socioeconomic status and African American race are strong risk factors for hospitalization and mortality from asthma. Public policy and healthcare resources need to be organized and directed more efficiently to this population.