Interlaboratory comparisons are presented of automated ion-exchange and gas chromatog-raphy measurements of D/L ratios of amino acids from an homogenized sample of aragonitic shells of the late Pleistocene clam S. giganteus. The mean and relative standard deviation determined by both analytical techniques for fifteen measurements of D-alloisoleucine/L isoleu-cine are 0.23%. Mean D/L ratios and relative standard deviations for seven amino acids mea-sured by gas chromatography are as follows: valine 0. 19%; alanine 0.45%; leucine 0.27%; proline 0.45%; aspartic acid 0.47%; phenylalanine 0.32%; and glutamic acid 0.21%. -- AATA