The analysis focused on marijuana, powdered cocaine, crack cocaine, heroin, phencyclidine (PCP), and Lysergic Acid Diethylamide (LSD). Price information was derived from undercover purchases by law enforcement personnel. The amount, purity, drug type, date, and location of the seizure or purchases were obtained from police and laboratory reports. The price and laboratory reports were matched using the property control number for each transaction. Marijuana prices have declined in the past 2 years. The availability and demand for marijuana have increased in the same period. The street price of powdered cocaine generally declined between July 1990 and the spring of 1993 and has slowly increased since the spring of 1993. The declining price is probably linked to an overall decline in cocaine's popularity. Purities have generally declined from January 1992 through April 1993. Heroin appears to have two distinct markets, one for low purity or injectable heroin and the other for high purity or snortable heroin. The prices of PCP and LSD appear to have dropped slightly since 1991. Figures, tables, and appended methodological information and table of weights and measures