BACKGROUND: While it is known that posterior cerebral artery (PCA) infarction may simulate middle cerebral artery (MCA) infarction, the frequency and localization of this occurrence are unknown. OBJECTIVE: To determine the frequency of PCA infarction mimicking MCA infarction and the territory of the PCA most commonly involved in this simulation. DESIGN: We studied 202 patients with isolated infarction in the PCA admitted to our stroke center to determine the frequency of PCA infarction simulating MCA infarction, the involved PCA territory, and the patterns of clinical presentation. RESULTS: We found 36 patients (17.8%) with PCA ischemic stroke who had clinical features suggesting MCA stroke. The PCA territory most commonly involved was the superficial PCA territory (66.7%), followed by the proximal PCA territory (16.7%) and both the proximal and the superficial PCA territories (16.7%). The principal stroke mechanism was cardioembolic (54.1%) in the superficial PCA territory, lacunar (46.2%) in the proximal PCA territory, and undetermined (40.2%) in both the proximal and the superficial territories. Among the 36 patients, the most common clinical associations were aphasia (13 patients), visuospatial neglect (13 patients), and severe hemiparesis (7 patients). CONCLUSIONS: Posterior cerebral artery infarction simulating MCA infarction is more common than previously thought. Early recognition of the different stroke subtypes in these 2 arteries may allow specific management.