Retrospectively, subarachnoidal hemorrhage can be misdiagnosed when the acute event did not bring the patient to medical attention, when clinical history is unclear and the CT scan is normal. Moreover, days after subarachnoid hemorrhage, cerebral vasospasm can result in neurological deficits that are indistinguishable from that produced by other causes of stroke. We report our experience with two patients who presented with symptoms of ischemia due to an arterial vasospasm that followed unrecognized rupture of an intracranial aneurysm. In both cases, CT scan failed to detect subarachnoid hemorrhage while MR detected the presence of signal changes in the subarachnoidal spaces associated with an ischemic stroke in one case. Neurological symptoms resolved completely after aneurysm treatment. MR can be a critical for the diagnosis of stroke secondary to vasospasm in order to prescribe an adapted treatment, avoid anticoagulant or thrombolytic therapy, and rapidly exclude the recently ruptured aneurysm to protect the patient from the risk of rebleeding.