The DUF program is used to track drug use among arrestees in 25 cities across the U.S. Every 3 months, a sample of 250 male arrestees at each site submits to a voluntary, anonymous interview about their drug abuse and treatment history as well as a urinalysis that tests for the presence of 10 drugs. The prevalence of cocaine use among arrestees in the 2 to 3 days prior to the urinalysis was 10 times greater than that found in surveys of the general population which measured drug use during the previous month. Cocaine was found in arrestees in all major cities participating in the DUF program and in all ages. The drug was used by all types of offenders. Female arrestees reported higher levels of injection than male arrestees; the subjects administered cocaine by smoking crack, freebasing, snorting cocaine powder, and injecting. The findings underscore the need to get a more comprehensive picture of drug trends in the country by considering the prevalence of drug use among the criminal and other hidden populations. 3 figures, 6 tables, and 8 references