1. The effect of d-aldosterone and dexamethasone on kallikrein release was studied in the isolated rat kidney perfused with modified Krebs-Henseleit buffer.
2. Animals received d-aldosterone or dexamethasone (10 μg/100 g body weight) daily for 3 days. Their isolated kidneys were then perfused with the same steroids at rates of 2.0–2.5 μg/min for 30 min.
3. Dexamethasone increased kallikrein release significantly (P < 0.001) both in urine and in venous outflow.
4. d-Aldosterone had no significant effect on kallikrein release, either in urine or in venous outflow.