To emphasize the limitations of magnetic resonance angiographic screening for intracranial aneurysms, we present the case of a patient with a false-negative screening result, unfortunately advancing to rupture of the aneurysm. An asymptomatic woman underwent magnetic resonance angiographic screening in an investigational setting. Three years later, she had an onset of sudden headache, after which her condition rapidly deteriorated. Severe subarachnoid hemorrhage and an intracerebral hematoma were diagnosed. Conventional angiography detected a small ruptured middle cerebral artery trifurcation aneurysm and two very small aneurysms. There are still limitations in the ability of magnetic resonance angiography to detect small or very small aneurysms. Even small-probability findings should always be confirmed or excluded by conventional angiography.