Multicomponent analyses were carried out for three types of urinary constituents: steroids, acids, and drugs and drug metabolites. The methods were based on gas-phase analytical techniques, which include the use of instruments and instrumental systems for gas chromatography, gas chromatography—mass spectrometry, and mass spectrometry—computerization. After isolating an analytical sample, we prepared derivatives in each instance. Gas chromatography was used for separations, mass spectrometry for identification. These procedures for obtaining metabolic profiles may be used in various ways, including studies of abnormal conditions, drug metabolism, and the effects of drugs on metabolic pathways, as well as for human developmental studies.