Previous studies have shown that lipids are synthesized at a constant rate in sebaceous glands and secreted onto the skin surface an average of 8 days after synthesis. As a result, measurement of the sebum content of a skin specimen of known surface area should allow calculation of the sebum production rate which had been occurring in vivo. In the present study, such measurements have been made on scalp skin specimens from 14 men. The amount of sebum in 4-mm punch biopsies was calculated from the squalene content of the specimens, as measured by quantitative thin-layer chromatography of lipid extracts. The average sebum production rate for the group was found to be 1.45 mg/10 sq cm/3 hr.