We compared the ocular hypotensive effects of four fixed-dose metipranolol-pilocarpine combinations in nineteen ocular hypertensive subjects and glaucoma patients. Each patient was tested with all of the study medications: vehicle alone, 0.1% metipranolol HCl + 2% pilocarpine HCl, 0.1% metipranolol HCl + 4% pilocarpine HCl, 0.3% metipranolol HCl + 2% pilocarpine HCl, and 0.3% metipranolol HCl + 4% pilocarpine HCl, in a single dose, randomized, double-masked, cross-over placebo-controlled trial. In addition, another eight age and baseline intraocular pressure (IOP)-matched subjects received 0.1% or 0.3% metipranolol HCl, while a similar group of 14 volunteers received 2% or 4% pilocarpine HCl. A two week washout period was instituted between the various groups of treatments. All four metipranolol-pilocarpine combinations were more effective than placebo or either medication alone in reducing the average IOP for up to 8 hours (p < 0.05 for each treatment group). Metipranolol HCl 0.3%, regardless of the pilocarpine concentration, demonstrated the most significant IOP lowering effect, reducing the IOP by 4.9 mm Hg or about 20% from baseline. However, 0.1% metipranolol HCl in combination with 4% pilocarpine HCl was found almost as effective with a 18.5% reduction in IOP from baseline, but a shorter duration of action. In conclusion, all metipranolol-pilocarpine combinations were more efficacious than either medication alone in a single-dose trial. Additional multiple-dose studies are needed to determine the long-term effectiveness and tolerance of combining 0.3% metipranolol HCl with either 2% or 4% pilocarpine HCl.