The authors' review of the health services literature since the release of the landmark Report of the Secretary's Task Force Report of Black and Minority Health in 1985 revealed significant differences in access to medical care by race and ethnicity within certain disease categories and types of health services. The differences are not explained by such factors as socioeconomic status (SES), insurance coverage, stage or severity of disease, comorbidities, type and availability of health care services, and patient preferences. Under certain circumstances when important variables are controlled, racial and ethnic disparities in access are reduced and may disappear. Nonetheless, the literature shows that racial and ethnic disparities persist in significant measure for several disease categories and service types. The complex challenge facing current and future researchers is to understand the basis for such disparities and to determine why disparities are apparent in some but not other disease categories and service types.