Racial/ethnic disparities in health have long been documented in a broad range of medical conditions in the United States. For example, Blacks have higher HIV incidence and AIDS-related mortality than do Whites., This article summarizes racial/ethnic differences in drug use and its consequences in the United States and proposes three key challenges to the study of disparities in drug use and its consequences. These are (a) patterns of drug use and misuse are complex, with different patterns of use of different drugs in different racia,/ethnic groups; (b) racial/ethnic differnces in use of drugs are not always associated with comparable differences in the consequences of drug use; and (c) the consequences of drug use are associated with drug use itself and other social/economic circumstances. Each of these challenges is discussed, and suggestions offered for future research that may help overcome them.