The baseline IOP was significantly higher in the experimental hypertensive eye than in the normal eye (29.9±2.7 versus 14.5±0.7 mmHg, p<0.0001). The mean IOP in the lasered eye treated with 0.4% GLC756 at 7:00 am decreased from 7:00 to 9:00 am, and then slightly increased until 1:00 pm. The maximal mean IOP decrease (8.5 mmHg) occurred one hour after application of the drug solution. A significant IOP lowering effect was observed 30 minutes after administration of the solution and remained low for two hours. No ocular (such as itching or pain) or systemic side effects to the medication were observed. The IOP in the control eye varied slightly from 7:00 am to 1:00 pm. GLC756 at a concentration of 0.4% significantly lowers the IOP in Rhesus monkeys with laser-induced ocular hypertension. This differs from previous studies performed in humans and rabbits. The IOP lowering effects are more pronounced, but only for a short period of time, in monkeys when compared to the effects observed in humans and rabbits.