We report the use of SP-1200 (Supelco Inc.) for quantitative gas-chromatographic determination of short-chain fatty acids (C2-C5) in stool water. The ratio of peak areas for these acids to that for 2-methylvaleric acid (internal standard) is linear for each acid from 60 to 1800 mg/liter. Lactic acid, occasionally present in stool in abnormally high amounts, is not detectable as the free acid on SP-1200, but is determined as its propyl ester on diethyleneglycolsuccinate.