Purpose: Primarily to determine the prevalence of various types of glaucoma and ocular hypertension in Wroclaw inhabitants aged 40-79 years. The second aim of the study was to determine the number of undiagnosed glaucoma cases in this population. Methods: A representative group of the Wroclaw population (4853 people aged from 40 to 79 years) was recruited by a proportional simple random sampling selection with stratification. All participants underwent the first, screening-stage examination, which included a medical history interview, intraocular pressure (IOP) measurement, anterior chamber depth assessment by the Van Herrick technique, and optic nerve head (ONH) assessment by means of indirect ophthalmoscopy (Volk's lens), confocal scanning laser ophthalmoscopy with a Heidelberg Retinal Tomograph (HRT) and scanning laser polarimetry by the GDx Nerve Fiber Analyzer (GDx). The second stage, in glaucoma-suspect patients only, included best corrected visual acuity, static perimetry, 24-hour monitoring of IOP, gonioscopy, and full eye examination with mydriasis. Glaucoma was diagnosed by the presence of any two of the following: characteristic morphological changes in the optic disc, glaucomatous visual field abnormalities, and intraocular pressure greater than 21 mmHg. Results: The overall prevalence of glaucoma was 1.6% (79 subjects). The prevalence increased with age from 0.4% in subjects belonging to the age group 40-49 years to 4.6% in people aged between 70 and 79 years. The prevalence of definite primary open-angle glaucoma was 1.0% (49 subjects). Normal-pressure glaucoma was diagnosed in 13 subjects (0.3%). Ocular hypertension was diagnosed in 92 subjects (1.9%). Conclusion: The prevalence of the different types of glaucoma was similar to that found in other white populations. Among the subjects examined, 79 had various forms of glaucoma and 71% of them had not previously been diagnosed. Undiagnosed glaucoma is a serious public health problem in Poland.