A process for efficiently, easily and stably producing tripeptides Val-Pro-Pro and Ile-Pro-Pro, which are useful as hypotensive drugs, anti-stress drugs, etc., by an enzymatic method. This process involves the step of cleaving a milk casein-containing material with a proteinase to form an intermediate peptide selected from the group consisting of a peptide containing the sequence Val-Pro-Pro but having no Pro other than this sequence, a peptide containing the sequence Ile-Pro-Pro but having no Pro other than this sequence, and a mixture of these peptides, and then cleaving the intermediate peptide with a peptidase to thereby give at least one of the tripeptides Val-Pro-Pro and Ile-Pro-Pro.