The influence of some peptidase inhibitors on oedema and plasma extravasation induced by bradykinin and carrageenan in rat paw was evaluate. Bradykinin-induced oedema in normal rats was increased by o-phenanthroline (3.10(-2) M), by captopril (10(-6) M to 10(-4) M), by lisinopril (10(-6) M to 10(-4), or by lisinopril (10(-5) M) in combination with apstatin (8.10(-5) M or 1.4 10(-4) M). It was not modified by phosphoramidon (10(-6) M to 10(-5) M) and by diprotin A (10(-3) M). It was increased by mergepta at high concentrations (2.10(-4) M). Mergepta did not increase the potentiating effect of captopril. Carrageenan-oedema in normal rats was increased by captopril (10(-5) M), lisinopril (10(-5) M) and apstatin (1.4 10(-4) M. It was not modified by mergepta (10(-4) M), phosphoramidon (10 (-5) M) and diprotin A (109-3) M). Des-Arg1-bradykinin and Des-Arg9-bradykinin have low oedema-promoting effects. Captopril (10(-5) M) increased the effects of bradykinin but not those of carrageenan in kininogen-deficit Brown Norway rats. Angiotensin-converting enzyme and aminopeptidase P appear to be main kinin-inactivating enzymes in rat paws. Carboxypeptidase N, neutral endopeptidase 24.11 and dipeptidyl(amino)peptidase IV do not play a significant role in this inactivation.