SummaryProfile analysis using capillary gas chromatography is applied in clinical chemistry to detect metabolic abnormalities. Examples are the increase of the urinary excretion of aromatic acids carrying a 4-hydroxyl group and the decrease of hippuric acid in liver cirrhosis, and the elevated concentrations and excretions of dicarboxylic, oxocarboxylic, and hydroxycarboxylic acids in diabetes mellitus. Gas chromatographic quantitations, in some instances using mass selective detection, are performed on clinically relevant constituents. An example is the investigation of plasma and urinary hippuric acid and 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid in different stages of renal diseases.