In 1956, West and Zimmerman reported a 'first case' of haemolytic anaemia, apparently caused by the use of nitrofurantoin (Furadantin). Since then, no further reports of this untoward effect of the drug have appeared in the literature.Recently a case of acute pyelonephritis treated with Furadantin, observed in the Paediatric Department of the Poriah Government Hospital in Tiberias, developed severe haemolytic anaemia when given this drug.Case Report S.I., a male baby of Iraqui origin, was admitted to this department at the age of 10 months. He was born normally, after a normal full-term pregnancy, the eighth child in the family. He had been breast fed all his life. No haemolytic disease was reported among the other children or the parents of the baby.A week before admission the infant was seen by a local physician on account of watery stools and vomiting. The treatment given was, reportedly, not effective.On admission, the baby was severely ill. He was semi-conscious; breathing was deep and rapid, giving the impression of severe metabolic acidosis. Skin turgor was practically non-existent. The liver edge was felt 3 cm. below the costal margin. The temperature was 390 C., and weight 7-3 kg.Laboratory examinations on admission showed the following results: Hb. 11*0 g. per 100 ml.; R.B.C. 3,900,000 per c.mm.; W.B.C. 41,000 per c.mm. (stab 7 %, neutrophils 68%, lymphocytes 18%, monocytes 1 %, eosinophils 1 %, plasma cells 2 %); reticulocytes 3%.Repeated urine examinations showed albumin +, white blood cells in large clumps and many granular casts. Stool examination was negative; stool culture was sterile for Shigella and Salmonella. Old tuberculin (5 TU) intracutaneously caused no local reaction 48 hours after injection.It was apparent that this baby was suffering from dehydration and electrolyte imbalance; he was therefore given intravenously physiological solutions with added base. During the 24 hours after admission 600 ml. of standard solution, saline and glucose 5 % aa, 400 ml. of 5% glucose solution and 50 ml. of 1/6 molar sodium lactate were administered. The baby was also given Neomycin 400 mg. daily, in four equal doses.On the day after admission the baby's condition was markedly improved; body weight reached 8-1 kg.; the number of stools was reduced and no clinical signs of acidosis were apparent. On the fourth day of hospitalization stools were normal in appearance and number.On the third day of his hospital stay, because of the urinary tract infection, a course of nitrofurantoin, 50 mg., three times a day, was started. On the fourth day of this treatment he passed red dark-coloured urine. Administration of nitrofurantoin was discontinued, after a total dose of 700 mg. had been given, a total of 90 mg. per kg. of body weight.On this day the red blood cell count was 980,000 c.mm. with a haemoglobin level of 3 g. per 100 ml. The reticulocyte count was 8 %, platelets 140,000 per c.mm.; haematocrit 17%. The total serum bilirubin level was 2-82 mg. per 100 ml.; urea 38-5 mg. per 100 ml. The total plasma protei...