Background and Purpose— Hyperintense vessels (HVs) have been observed in fluid-attenuated inversion recovery imaging of patients with acute ischemic stroke and been linked to slow flow in collateral arterial circulation. Given the potential importance of HV, we used a large, multicenter data set of patients with stroke to clarify which clinical and imaging factors play a role in HV. Methods— We analyzed data of 516 patients from the previously published PRE-FLAIR study ( PRE dictive value of FLAIR and DWI for the identification of acute ischemic stroke patients ≤3 and ≤4.5 hours of symptom onset—a multicenter study) study. Patients were studied by MRI within 12 hours of symptom onset. HV were defined as hyperintensities in fluid-attenuated inversion recovery corresponding to the typical course of a blood vessel that was not considered the proximal, occluded main artery ipsilateral to the diffusion restriction. Presence of HV was rated by 2 observers and related to clinical and imaging findings. Results— Presence of HV was identified in 240 of all 516 patients (47%). Patients with HV showed larger initial ischemic lesion volumes (median, 12.3 versus 4.9mL; P <0.001) and a more severe clinical impairment (median National Institutes of Health Stroke Scale 10.5 versus 6; P <0.001). In 198 patients with MR angiography, HVs were found in 80% of patients with vessel occlusion and in 17% without vessel occlusion. In a multivariable logistic regression model, vessel occlusion was associated with HV (OR, 21.7%; 95% CI, 9.6–49.9; P <0.001). HV detected vessel occlusion with a specificity of 0.86 (95% CI, 0.80–0.90) and sensitivity of 0.76 (95% CI, 0.69–0.83). Conclusions— HVs are a common finding associated with proximal arterial occlusions and more severe strokes. HVs predict arterial occlusion with high diagnostic accuracy.