Following a seventeen weeks study including 110 patients with open-angle glaucoma, 81,8% of the patients treated by timolol, administered twice a day, had a satisfactory control of their intraocular pressure, against only 41,8% of those patients treated by pilocarpine, administered four times a day. The side effects liable to timolol are clinically reduced, in a osit with pilocarpine which is followed by a series of well-known subjective and objective signs often causing discomfort to the patients.