Published evidence appears to be inadequate to establish whether there is significant hazard in administering systemic medications with anticholinergic properties to patients who have primary open-angle glaucoma. Tests have been made in 28 patients with this type of glaucoma, showing that, although by applying an anticholinergic agent directly to the eyes it was possible to cause a prompt rise of at least 5 mm Hg in ocular pressure in half of the patients, when atropine sulfate was administered orally (two doses of 0.6 mg), it did not appreciably influence the pressure in a test period of seven to eight hours. The influence of cumulative repeated doses over a longer time remains to be determined.