A detailed study of Dicephalus dipus tetrabrachialis which could not be surgically corrected because of anatomic complexity is presented. The cardiovascular, urinary and nervous systems were interconnected. The gastrointestinal system was duplicated up to the mid-ileum with a single colon and rectum. A large fused liver, two, gall bladders with two bile duct systems, two pancreas and two spleens were present. Genital organs comprised of four testes. There was extreme cerebellar hypoplasia and congenital malformation of the heart in the incomplete twin.