The following case report, I believe, represents the first reported case of spontaneous hypersensitivity to immune serum globulin (human). A 15-week-old male infant was brought to my office on Oct. 10, 1958. He had been exposed to an uncle living in the same house who was ill with infectious hepatitis. Because of this, the infant was given 0.6 cc. of immune serum globulin (human) which had been obtained from the Maryland State Health Department. The injection was made into the upper outer quadrant of the left buttock; a 2-cc. syringe and a 20-gauge needle which had been water-sterilized were used. The plunger was pulled back to assure that the needle was not in a vein and no blood was received. Within 60 seconds after injection the baby became limp, was flushed all over, suddenly turned cyanotic, and stopped breathing. Within 15 seconds the baby was given an injection of 1