1. Acute oral administration of metoprolol and propranolol to ten normal males resulted in equal reduction in heart rate both supine and after passive tilting to 60°.
2. Tilted systolic blood pressure was reduced by both agents but metoprolol alone reduced supine systolic blood pressure.
3. Tilted but not supine diastolic blood pressure was reduced by both agents.
4. Metoprolol and propranolol both reduced the rise in plasma renin activity induced by tilting.
5. No effect of tilting was observed on plasma aldosterone.