Patients with giant cell arteritis (GCA) generally present with cranial ischemic manifestations that are directly related to vascular involvement. They may also experience strokes in the territory of the carotid or the vertebrobasilar artery. We conducted the current study to assess the frequency and predictors of strokes in general, and of vertebrobasilar stroke in particular, at the time of diagnosis in a series of 287 consecutive patients with biopsy-proven GCA diagnosed over a 27-year period at the single hospital for a well-defined population of northwestern Spain.During the study period, 8 (2.8%) patients had strokes (1 in the carotid and 7 in the vertebrobasilar territory) between the onset of symptoms of the disease and 4 weeks after the onset of corticosteroid therapy. Six of the 7 patients with vertebrobasilar stroke were men. In most cases the vertebrobasilar stroke occurred after the onset of corticosteroid therapy. Smoking history was more common among patients with vertebrobasilar stroke (p = 0.01). Patients with vertebrobasilar stroke more commonly had permanent visual loss due to arteritic involvement of ophthalmic branches derived from the internal carotid (3/7; 42.9%) than the rest of GCA patients (33/280; 11.8%) (p = 0.05). Patients with strokes had higher hemoglobin values (13.2 +/- 1.5 g/dL) than patients without (11.7 +/- 1.6 g/dL) (p = 0.009). Moreover, only 1 (14.3%) of the 7 patients with vertebrobasilar stroke had anemia compared to 157 (56.1%) of the remaining 280 patients (p = 0.05). The best predictors of stroke were permanent visual loss (odds ratio [OR], 5.42) and arterial hypertension (OR, 5.06). In contrast, women (OR, 0.10) and patients with anemia at the time of disease diagnosis (OR, 0.11) had a significantly reduced risk of suffering strokes. Smoking history was the best positive predictor of vertebrobasilar stroke (OR, 5.22). In contrast, a reduced risk of suffering vertebrobasilar strokes was found in individuals who had anemia at the time of GCA diagnosis (OR, 0.13).Results of the current study show an increased risk of strokes, in the vertebrobasilar territory in particular, at the time of GCA diagnosis. Patients with biopsy-proven GCA and traditional cardiovascular risk factors or permanent visual loss have an increased risk of suffering strokes. Results also suggest a potential protective role of anemia against the development of these cerebrovascular complications.