• Ocular hypotensive actions of N-demethylated carbachol hydrochloride (DMC) were studied in patients with open angle glaucoma; 1% pilocarpine hydrochloride solution was used as a reference. Although 1% pilocarpine seemed to be slightly more potent than 6% and 9% DMC solutions, DMC solutions were devoid of the noticeable side effects produced by pilocarpine. In all cases, maximum ocular hypotensive actions were observed six hours after the single-drop medication and were determined as 4.2, 4.6, and 4.8 mm Hg with 6% DMC, 9% DMC, and 1% pilocarpine, respectively.