Nipradilol (CAS 81486-22-8) is a non-selective beta-blocker with alpha-1 blocking and nitroglycerin-like vasodilating activities. In the present communication, the long-term efficacy and safety of nipradilol were investigated and the efficacy, safety and utility of topical nipradilol and timolol (CAS 91524-16-2) were compared in patients with primary open-angle glaucoma or ocular hypertension. In the long-term study, nipradilol for 1 year (52 weeks) was performed by registration method. 67 out of 68 patients were subjected to analysis and 57 patients (83.8 %) completed 52-week instillation. 0.25 % nipradilol was applied twice daily to patients. As a result, intraocular pressure (IOP) decreased significantly by 4.0 mmHg to 4.8 mmHg compared with the baseline without tachyphylaxis. The incidence of adverse events was 12.5 % at 52 weeks by analysis with Kaplan-Meier life-table method. It showed no significant trend of increase after 3 months. In the multi-centered double-masked comparative randomized study, 0.25 % nipradilol was assigned to 96 patients and 0.5 % timolol to 100 patients. Each patient was instilled nipradilol or timolol twice daily for 8 weeks. IOP significantly decreased by 4.2 mmHg and by 4.7 mmHg at 8 weeks and the incidence of adverse events was 10.5 % and 12.1 % in the nipradilol and timolol group, respectively. No significant between-group difference in IOP reduction or incidence of adverse events was seen. Topical nipradilol showed long-term ocular hypotensive effects and clinical safety in a 52-week study, and its efficacy and safety equivalent to timolol was confirmed in a 8-week comparative study.