Recent scientific evidence indicates that marihuana has very harmful biochemical and cellular effects for the long-term user. This monograph reports the latest findings in the identification of specific chemicals contained in the cannabis plant and in the smoke resulting from its pyrolysis and produced in the body through biotransformation. For the first time, the inhibitory effects of cannabinoids on cell proliferation and DNA formation, in vitro and in vivo, and sperm formation is described. Micromethods of detection in body fluids, urine, plasma, and saliva are also included.