Background: Propiverine hydrochloride (P4) is an antimuscarinic drug used in overactive bladder syndrome. Methods: Two studies were performed: one in 24 patients with open-angle glaucoma (OAG) treated with topical beta-blockers, one in 24 patients with narrow-angle glaucoma (NAG) treated with pilocarpine +/- topical beta-blockers. Patients were treated in randomized, place-bo-controlled, double-blind parallel-group fashion (15 : 9 attribution to P4 vs. placebo (PL)). Treatments: Single-blind PL dose in the morning of day 1 for baseline; double-blind 15 mg P4 or matched placebo t.i.d. from the afternoon of day 1 until the morning of day 7. Results: In the morning of day 7, trough mean serum P4 concentrations were 169.4 ng/mL (CV (coefficient of variation): 0.55) and 140.7 ng/mL (CV: 0.56) in OAG and NAG; at 3:15 hours after dosing: 237.4 ng/mL (CV: 0.47) and 212.4 ng/mL P4 (CV: 0.38), respectively. P4-treatment led to a prompt (OAG) or more gradient (NAG) increase in pupil diameter (PUD), with a maximum difference from PL of 0.97 mm (95% confidence interval (CI): 0.67 - 1.27) and 0.87 mm (95% CI: 0.36 - 1.39) in OAG and NAG, respectively. However, there was no average increase in intraocular pressure (IOP) or increase in note-worthy safety-relevant individual IOP values (or changes thereof). There was no effect on visual acuity or accommodation. Conclusions: 1-week treatment with P4 appeared to be safe 1) in OAG patients treated with topical (beta-blockers and 2) in NAG patients treated with topical pilocarpine +/- beta-blockers, irrespective of whether the eyes had previously, been treated with glaucoma surgery or laser therapy.