1. Thirty-six patients with essential hypertension, were randomly allocated to double-blind treatment with either metoprolol (100–200 mg/day) or pindolol (5–10 mg/day). The effects upon blood pressure and peripheral blood flow were determined. Both drugs reduced blood pressure significantly.
2. Heart rate was significantly reduced by metoprolol but not by pindolol.
3. Vascular resistance at maximal dilatation was not changed by either compound.
4. At rest, pindolol reduced vascular resistance in the calf by 14% (P < 0.05) but metoprolol tended to increase the resistance slightly. The difference in effect was also significant (P < 0.005).
5. During leg muscle work there were no changes in vascular resistance in the forearm with either compound.
6. We conclude that pindolol appears to reduce blood pressure at least partly through vascular mechanisms, in contrast to metoprolol. The response to sympathetic stimulation induced by physical exercise does not differ between metoprolol- and pindolol-treated patients.