The preparation of leucylalanine-2-C¹⁴ /

L-Leucyl-DL-alanine-2-C¹⁴ with a specific activity of 2.5 uc/mg was prepared in an over-all yield of 22% from alanine-2-c¹⁴. Thirty-three percent of the starting activity was recovered as DL-alanine-2-C¹⁴. A byproduct of the reaction in a yield of 22% was tentatively identified as an intra-or intermolecular anhydride of the peptide.