We report a case of acute intermittent porphyria presenting with variable symptoms and signs such as hypertention, polyneuropathy, syndrome of inappropriate secretion of antidiuretic hormone and cerebral infarction. A 47 year-old female patient entered hospital with abdominal pain followed by generalized seizure. She was diagnosed to have acute intermittent porphyria in consequence of Watson-Schwartz test and ${delta}$-ALA in 24 hours urine, but died of respiratory failure.