Studies were conducted on the biotransformation of the growth-regulating diphenylacetylglycine. For this purpose this substance was radio-labelled prepared from (14COOH)diphenylacetic acid and glycine. In plants of wheat of the sort "Remo", barley of the sort "Certina", and tomatoes of the sort "Harzfeuer" the agent undergoes only a low metabolism. Diphenylacetic acid is not formed, therefore, the peptide linkages are rather stable. Only little quantities of more polar metabolites have been found, one of them being chromatographically indicated as diphenylacetylglycine glucose ester.