Qualitative and quantitative analyses of sterol derivatives in the tissue of cholesteatoma and cholesterol granuloma were performed by gas-liquid chromatography, mass spectrometry and mass fragmentography after the extraction of total lipids with organic solvents. Cholesterol was the major component in both tissues. The molar ratios of cholesterol to lipid-bound phosphorus in cholesterol granulomas were higher than those in cholesteatomas. In addition, Δ7-cholestenol (lathosterol) was contained in all tissues of cholesteatoma examined. However, cholesterol granuloma tested did not contain Δ7-cholestenol, indicating that the metabolism of cholesterol differed from that in cholesterol granulom