Metabolic profiles can be obtained by gas phase analytical methods for many types of human metabolic products. These include urinary steroids, urinary and blood sugars and sugar alcohols, urinary and blood acids; compounds of the Krebs cycle and related substances; and drug metabolites in blood or urine. Changes in profiles can be studied for pathologic circumstances and after drug therapy. The methods are particularly useful for drug metabolism studies. The instrumental techniques are those of combined GC-MS. Multicomponent analyses are carried out by temperature programming, and the identity of each component is determined by MS. Appropriate derivatives must be prepared for each type of separation.