A case report of intermittent acute porphyria in a 20 years old female patient. First symptoms appeared at 15 years of age, and were represented by periodical abdominal pains. Neurological disturbances appeared soon after a surgical stress due to abdominal operation (laparotomy). There are no cases of porphyria with clinical signs in the family, but the father and four brothers present porphobilinogen in the urine. At clinical examination the patient's precarious general condition was noticed, although all organs and systems were normal. The patient presented changes of mood with irritability, alternating with stages of complete apathy. The neurological examination shower flacid sesitivo-motor tetraplegia with sphincter disorders. Other examinations excluded functional disturbances of liver and kidneys, but revealed the existence of a leucocitosis without any apparent infectious cause and a discrete and transitory glycosuria. Two electroencephalograms were carried cut at an interval of three months : both showed a diffuse paroxystic dysrhythmia; it must be mentioned that the patient never suffered of epilepsy or any similar illness. Electrodiagnosis, including electromyography, showed signs of serious affection of the peripheral motor neuron in almost all muscular territories of the limbs. Dermatological examination revealed cutaneous lesions which had no relation to porphyria. The anatomo-pathological examination of a muscular biopsy showed atrophy of the striated muscle. Electrophoresis showed a relative increase of globuline and decrease of albumino-globuline relation in blood serum and cerebro-spinal fluid; in both the increased value of globulines was due to a percentual augmentation of α2 and γ globulines. Coproporphyrin and porphobilinogen was found in the urine (Watson and Schwartz's technique).