BACKGROUND AND PURPOSE: Transient visual symptoms (TVS) are common complaints. They can be related to transient ischemic attacks, but the nature of the symptoms often remains uncertain, and data on prognosis are scarce. We studied the prevalence, presentation, and effect of different types of TVS, paying particular attention to the association with high-risk pathology of embolism. METHODS: A total of 2398 patients with suspected transient ischemic attack admitted to the SOS-TIA clinic between January 2003 and December 2008 underwent immediate evaluation and treatment. RESULTS: Eight hundred twenty-six (34.5%) patients had TVS, including 422 (17.6%) patients with isolated TVS. Transient monocular blindness was the most frequent TVS (36.3%), followed by diplopia (13.4%), homonymous lateral hemianopia (12.3%), bilateral positive visual phenomena (10.8%), and lone bilateral blindness (4.5%). Positive diffusion-weighted imaging was found in 11.8%, 8.1%, 8.1%, and 5.0% of patients with homonymous lateral hemianopia, diplopia, lone bilateral blindness, and transient monocular blindness, respectively. Among 1850 patients (595 patients with TVS) with definite/possible transient ischemic attack or minor stroke, a major source of embolism of cardiac or arterial origin was found less frequently in patients with isolated or nonisolated TVS than in patients without TVS (19.6%; 19.7% versus 28.1%, respectively; P<0.001). However, we found a higher rate of atrial fibrillation in patients with homonymous lateral hemianopia (23.2%) than in patients with other TVS (4.0%; adjusted odds ratio, 6.71; 95% confidence interval, 2.99-15.06) or nonvisual symptoms (9.1%; adjusted odds ratio, 4.39; 95% confidence interval, 2.26-8.50). CONCLUSIONS: Approximately 20% of patients with TVS had a major source of embolism detected, requiring urgent management. Atrial fibrillation was particularly frequent in patients with transient homonymous lateral hemianopia.