Highlights from this report include: for the period January 1987 - December 1989, mentions for cocaine in emergency room (ER) drug abuse episodes increased for the total Drug Abuse Warning Network (DAWN) system, and in 14 of the 21 metropolitan areas; a significant decrease in cocaine mentions was observed in the New York area; mentions for heroin/morphine increased in the overall DAWN system in the first half of 1987 but then decreased by the last half of 1989, and increasing trends were noted in 12 of the 21 metropolitan areas; decreases for heroin/morphine mentions were noted in Detroit and New Orleans; mentions for marijuana increased in 6 of the 21 areas, while significant decreases were noted in 4 of the metropolitan areas; no increases in ER cases involving PCP were found in any of the metropolitan areas over the 3-year period, while 7 areas showed decreases in PCP/PCP combination mentions. In medical examiner (ME) cases, drug abuse deaths involving cocaine increased from 625 as of December 1986 to 1,254 as of June 1989; and heroin/morphine mentions increased from 720 as of December 1986 to 986 as of June 1989. This report presents trends in the semiannual number of mentions of selected drugs in ER drug abuse episodes for the period January 1987 - December 1989 and ME cases for the period July 1986 - June 1989, as reported through the DAWN system. Data were obtained from 448 participating ERs in 21 metropolitan areas and 79 MEs or coroners in 26 metropolitan areas in the continental United States. Trends in drug mentions are tabulated for 6-month intervals over a 3-year period. Tables and appendixes