Data are presented for the use of marijuana, cocaine, opiates, amphetamines, PCP, and "any drugs." More than one-half of the male arrestees tested during the fourth quarter showed positive for a drug. In most cities, two to four times more drug users were detected by urinalysis than by self-reports. At least 45 percent of arrestees charged with violent crimes or income-generating crimes tested positive for a drug. Between 13 percent and 46 percent of male and female arrestees reported having ever injected drugs, including cocaine, amphetamines, and heroin. Between May 1984 and November 1988, cocaine use in Washington, D.C., tripled from 18 percent to 62 percent. In Philadelphia, 82 percent of the male arrestees in Philadelphia tested positive for any drugs, 75 percent for cocaine. Amphetamines continued to be found primarily in arrestees tested in San Diego, Phoenix, Portland, and Dallas. Graphic and tabular data.