Placebo and propranolol (Inderal) in doses of 20, 40, and 80 mg were given in a single-blind test to two groups of six ocular hypertensives. The groups consisted of patients with an intraocular pressure ranging from 20 to 29 mmHg and 30 to 39 mmHg. The doses were given 48 hours apart and administered after fasting 12 hours. IOP by Goldmann applanation tonometer, systemic blood pressure and pulse rate in the supine position were recorded hourly before and after administration. In both groups a decrease in mean IOP was noted after one hour and this reduction reached its maximum three hours after the administration of propranolol. The absolute reduction was greater in the group with the highest initial IOP and in both groups the fall in mean IOP showed a clear dose-dependent correlation. The simultaneous mean decrease in pulse rate was also dose-correlated, but reached its maximum two hours after administration. The fall in systemic blood pressure was only moderate and showed no obvious dose-dependence.