A 67-year-old woman developed a sudden onset headache and left hemiparesis. Emergency medical technicians found that she was conscious, but had left hemiparesis. On arrival, she had an isolated headache without any neurological deficits, however, suddenly became comatose during a head CT examination, which demonstrated a subarachnoid haemorrhage. The head CT angiography on the second day revealed a cerebral aneurysm at the right middle cerebral artery, which was clipped on the same day. The patient demonstrated left haemiplegia and total aphasia after the operation, however, the neurological deficit gradually subsided and discharged on foot in 4 months without any deficits. Some patients with a subarachnoid haemorrhage may demonstrate transient neurological deficits, like those occurring during an ischaemic stroke, so emergency medical technicians and physicians should pay attention to treat such patients gently to avoid the re-rupture of a cerebral aneurysm, especially if the patient has headache symptoms.