Responses of sterol, fatty acid, sterol ester and triglyceride on a quantitative thin layer chrornato-graphic apparatus which was equipped with a flame ionization detector were determined using with six kinds of neutral lipid mixtures. These responses were represented as relative responses against to tri-glyceride response and converged within maximum error of 5-10% (S.D.) over a range of loads (2-10 μg lipid). All of the relative responses were in proportion to the weight ratio. It was found that the method is very superior and convenient means for the quantitative estimation of neutral lipid compositions.