The angiographic and pathologic features of an endodermal sinus tumor (EST) arising from the retroperitoneum in a 19-month-old boy are presented. Although rare instances of extragonadal origin of EST have been reported, this is the first detailed description of the angiographic abnormalities. The angiographic appearance was that of a primarily retroperitoneal tumor with parasitized feeding arteries from the liver and right kidney, early filling venous radicles, sinusoidal pooling of contrast material, and inferior vena caval obstruction.