During histological and physiological investigations of black vultures (Coragyps atratus) dissection revealed the presence of an "organ", the supracloacal chromolipoid body, which has no counterpart among other warm blooded animals. The organ occurs in both sexes and in birds of different ages. It is located in the median sagittal plane dorsal to the cloaca. It is enveloped by a smooth muscle-connective tissue capsule and has a rich blood supply. The supracloacal body is yellow-brown in color being composed chiefly of islands of pigment cells.Histochemically, the pigment is a chromolipoid as defined by Ciaccio.