The effect of a newly developed ophthalmic solution containing both 0.5% timolol and 2% resp. 4% pilocarpine was compared with that of timolol 0.5% eye drops alone in 93 patients with manifest simple or capsular glaucoma or ocular hypertension. The medications were administered twice daily. The absolute additive effect of pilocarpine was small, although the combined solutions caused a statistically significantly greater reduction of the intraocular pressure than that achieved by timolol alone. This additional effect appeared to last at least 12 h. The effect of the test solutions containing 2% resp. 4% pilocarpine was very similar. Apart from the well-known effects of the pilocarpine-induced miosis, the combined test medications were generally well tolerated.