Drug abuse is so prevalent, that it should be considered a possible cause of or significant contributor to a person's death, especially when the death is sudden, unexpected, or when circumstances suggest that the manner of death may not involve natural causes. With the instrumentation and methods now available to forensic pathologists, most drugs and poisons can be detected at very low levels in the body. This chapter first identifies and discusses some of the difficulties in collecting, analyzing, and interpreting data from a postmortem toxicology. One section of the chapter presents a formula for calculating the amount of drug necessary to produce a given blood level; however, since it is most helpful when examining living patients, it should be used more as an estimation in death investigations. Other sections of the chapter address procedures for determining the presence and amounts of the following drugs in the body of a deceased: ethyl alcohol, cocaine, opium, heroin, amphetamines, barbiturates, LSD, marijuana, phencyclidine (PCP), designer drugs, inhalants, GHB, short-acting compounds, and prescription drugs. Information is provided on the effects of these various drugs or drug categories and the forensic procedures to use in determining their involvement in a death under investigation. 35 photographic exhibits and 34 references