1. 1. A comparative investigation of the free amino-acids and related compounds in the developing embryos of Rana temporaria, Bufo bufo, Bombina variegata, Xenopus laevis, Triturus alpestris, and T. helveticus has been carried out by ion-exchange chromatography. 2. 2. In addition to the common amino-adds several ninhydrin-positive derivatives including phosphoecrine, paosphoethanalamine, glycerophosphoethanolamine, alpha-aminoacidic acid, sarcoaine, cystathioaine, 3-methyl-histidine, and glutathione were identified. With the exception of certain minor differences embryos of the 6 amphibian species contain essentially the same major ninbydrin-poritivc components. 3. 3. Among the peptides one is particularly rich in serine. 4. 4. Acid hydrolysis indicates the presence of bound glycine. 5. 5. The possible role of these compounds in embryonic development is discussed.