This report describes a headspace procedure suitable for the gas chromatographic assay of acetaldehyde, methanol, ethanol and various other volatile substances in biological samples. Carbopack B coated with 5% Carbowax 20-M is compared to Carbopack C coated with 0.2% Carbowax 1500. Assay range, linearity and precision are reported for the Carbopack B material.