A random sample of 768 clinic patients 40 years or older were screened by a technician utilizing Schiötz tonometry. All patients with an intraocular pressure of 20 mm Hg or more were referred for ophthalmological evaluation. The prevalence of frank glaucoma and suspected glaucoma in this infirm population was 1.8% and 2.5%, respectively. The cost of detecting frank or suspected glaucoma decreased in the second half of the study due to a decrease in the number of false-positive tests. These findings suggest that all clinic patients 40 years or older should be screened for glaucoma. Because many internists are reluctant to screen for glaucoma and because there are large numbers of false-positive tests by those who do tonometry episodically, we suggest that technicians do glaucoma screening.