A radiochemical method based on dansylation of plasma samples with Dansyl-chloride and thin layer chromatography on polyamide sheets is presented for the quantitative individual determination of plasma amino acids in very small blood samples. The results are first corrected with a norvaline internal standard and secondly with ~pecific recovery factors for each amino acid. The results agree closely with other methods and with already published plasma normal amino acids values in healthy adult rats.