A case of aortic jet collapse and rupture which came to postmortem examination is reported. The complication occurred in a newborn undergoing angiography with an end-open, indwelling umbilical catheter and an effective injection pressure of 500 PSI. At the time of autopsy, a complete rupture of the aortic wall through all layers, a small hematoma confined by adventitia, and a dissection of the media were found. It is concluded that the aorta in new-borns is easily collapsible and easily damaged by the forward jet from a high pressure injection of contrast medium. For this type of angiography, maximal effective injection pressures of 275 PSI or flow rates not exceeding 6 cc. per second are suggested.