Objective: To determine the risk factors for permanent visual loss (PVL) in patients with biopsy-proven giant cell arteritis (GCA) and the usefulness of the factors in clinical practice., Methods: From 1976 through 2015, the clinical charts and laboratory results of 339 patients with biopsy-proven GCA were recorded prospectively at the time of diagnosis. We used multivariable logistic regression analysis to determine which of 24 pretreatment characteristics were associated with PVL., Results: Visual ischemic manifestations occurred in 108 patients, including PVL in 53 (16%), bilaterally in 15 patients (28%). The independent predictors associated with an increased risk of PVL were age (OR 1.06, 95% CI 1.01-1.12, p = 0.01), a history of transient visual ischemic symptoms (OR 2.62, 95% CI 1.29-5.29, p < 0.01), and jaw claudication (OR 2.11, 95% CI 1.09-4.10, p = 0.03). The presence of fever (OR 0.30, 95% CI 0.14-0.64, p < 0.01) and rheumatic symptoms (OR 0.23, 95% CI 0.10-0.57, p = 0.001) were associated with a markedly reduced risk of developing visual loss (3.7% if features were both present). No laboratory variables were independently associated with PVL., Conclusion: The visual ischemic risk of untreated GCA can be readily estimated upon simple clinical findings, but not laboratory variables. However, we did not identify a subgroup of patients carrying no risk of developing visual loss. Glucocorticoid treatment remains, therefore, urgent for any patient with a high clinical suspicion index.