Consumption of psychoactive substances may impair driving performance. Because of the diversity of the substances, toxicologists have to develop analytical strategies which allow the detection and the quantification of drugs in biological samples. The analytical strategy described here is composed of three steps: screening, confirmation, and quantification. For screening, immunological tests and chromatography techniques (GC and HPLC) are often used. For confirmation, identification by means of mass spectrometry is required, and quantification is often realized through chromatographic techniques