Sweat is an alternative biological matrix useful to detect drugs of abuse intake. It is produced by eccrine and apocrine glands originating in the skin dermis and terminating in secretory canals that flow into the skin surface and hair follicles. Since many years it has been demonstrated that endogenous and exogenous chemicals are secreted in this biological sample hence its collection and analysis could show the past intake of xenobiotics. From the seventies the excretion of drugs of abuse has been investigated in human skin excretion; later in nineties forensic scientists began to experiment some techniques to trap sweat for analyses. Even if the use of skin excretions for drug testing has been restricted mainly by difficulties in sample recovery, the marketing of systems for the sample collection has allowed successful sweat testing for several drugs of abuse. In the recent years sweat testing developed a noninvasive monitoring of drug exposure in various contexts as criminal justice, employment and outpatient clinical settings. This paper provides an overview of literature data about sweat drug testing procedures for various xenobiotics especially cocaine metabolites, opiates, cannabis and amphetamines. Issues related to collection, analysis and interpretation of skin excretions as well as its advantages and disadvantages are discussed. Moreover the chance to apply the technique to some particular situation such as workplace drug testing, drivers, doping or prenatal diagnosis, the comparison between sweat and other non conventional matrices are also reviewed. According to literature data the analysis of sweat may be usefully alternative for verifying drug history and for monitoring compliance.