In a case-control study using an exploratory health questionnaire, we examined the relationship between primary open angle glaucoma (POAG) and a variety of personal characteristics and potential toxic exposures in patients in a general eye service. There were 83 patients with definite POAG, 121 POAG suspects, and 237 controls. Using multiple logistic regression analysis for simultaneous evaluation of potential risk factors, we found that black race (rate ratio = 6.8; 95% confidence interval [CI] = 2.8 to 16.0) and untreated systolic hypertension (rate ratio = 5.8; 95% CI = 2.2 to 15) were the most important risk factors. Current cigarette smoking was also associated with glaucoma (rate ratio = 2.9; 95% CI = 1.3 to 6.6). Suggestive associations were found with family history of glaucoma, definite or borderline diabetes, and myopia. The effects of many of these personal characteristics and exposures as risk factors were also noted for the glaucoma suspect group, though not as strongly as for the definite glaucoma cases.