Abstract: Cholesterol can be adsorbed on the surface of the static mercury drop electrode, and then oxidized during anodic potential scan. The stripping peak potential in differential pulsevoltammetry is at-0.08 V in 0. 1 mol/L K₂HPO₄--KH₂PO₄ buffer solution. The stripping current islinear with the concentration of cholesterol in the range of 10^-7～10^-6 mol/L. The detection limitfound is 8×10^-8 mol/L after a 5 min preconcentration period. The adsorption and oxidation mechani-sms of cholesterol at the mercury electrode were been explored. The experimental conditions for mea-suring free cholesterol in human sera were examined.