We evaluated the efficacy and safety of 0.5% levobunolol HC1 (Vistagan®) in 2,041 glaucoma patients at 143 sites in the Federal Republic of Germany. This study was a 3-month, open-label, noncomparative trial of levobunolol administered twice daily. Eighty-five percent of the patients completed the study period with well-controlled intraocular pressure (IOP). Treatment was discontinued in the remaining 15%: 7% for adverse reactions, 1% for lack of drug efficacy, and 7% for reasons unrelated to the study treatment. Efficacy, ocular drug tolerance, and systemic safety were judged as good to very good in approximately 80% of the patients. This large, postapproval study confirms previous findings of several well-controlled clinical trials indicating that levobunolol is an effective drug for the treatment of elevated IOP and is safe and comfortable for most patients