The arterial supply of the human spinal cord was investigated in detail using microangiography and binocular microscopy after the specimens had been made transparent. (1) The arterial tributaries to the spinal cord were found to come from the anterior radicular arteries in a total number varying from 3 to 15, and from posterior radicular arteries numbering 14 to 25. The location of the great anterior radicular artery varied from Th8 to L3. This artery was most often the only ventral feeder to the lower cord. (2) The surface arteries of the spinal cord were mainly derived from the posterior longitudinal arteries with only tiny anastomoses from the anterior spinal artery. The pial artery plexus was best developed over the posterior surface of the cord, particularly at levels of the enlargements. (3) The intramedullary central part us supplied by the anterior spinal artery and a peripheral part mainly from the posterior longitudinal arteries. Anastomotic connections between the two systems or between individual arteries within the two systems could not be observed.