The 1990 National Household Survey on Drug Abuse is the 10th study in a series of national surveys to measure the prevalence of drug use among the American household population aged 12 and over. This report, which presents estimates of drug use prevalence for the civilian and noninstitutionalized population of the United States, is intended as a companion piece to the other reports generated for the 1990 National Household Survey. Population estimates are presented separately for the total population and for Whites, Hispanics, and Blacks. For each drug there are eight tables which are arranged to facilitate group comparisons. The data for the total population are presented by sex for each of the four age groups. Data in the remaining seven tables for each racial or regional category are presented first by age, then by sex, and finally for the total population in that racial or regional category. A prevalence section presents data for the illicit or nonmedical use of any drug, and for prevalence of the individual licit and illicit drugs, with separate data for the prevalence of phenocyclidine (PCP), heroin, cocaine and amphetamine use. The frequency and regularity of drug use during the past year are reported. Information is provided on the frequency of use in the past year for marijuana, cocaine, and alcohol. (LLL)