The child described was 1 year 1 month, and was well developed and healthy. He underwent SUD following the doctor's examination in the presence of the doctor, nurse and mother. The case terminated fatally despite adequate resuscitation. The post mortem examination did not reveal the cause of death. The authors feel that the case supports their previously presented hypothesis of infant neurocirculatory dystony as the cause of SUD. When the infant mortality drops below 15% SUD remains as one of the chief causes of infant death.