The aroma fraction from the fat of high-quality raw-milk Cheddar cheese was isolated by centrifugation of the intact cheese and passing the recovered fat through a molecular still at 40°C. The aroma fraction was separated by gas chromatography on packed columns containing polar and nonpolar phases and by programmed-temperature capillary-column gas chromatography. The effluent from the latter column was admitted directly to the inlet of a rapid-scan mass spectrometer enabling concurrent recordings of mass spectra for each chromatographic peak. The aroma fraction was separated into approximately 130 components by the capillary column. By correlation of gas chromatography and mass spectral data, most of the major neutral components were characterized. These included aldehydes, methyl ketones, primary and secondary alcohols, esters of the primary and secondary alcohols and fatty acids, γ-lactones, and the isomeric lactides of lactic acid.