Abstract: A Judkins-type angiographic catheter adapted to be inserted in a coronary artery for measuring the velocity of coronary blood flow, comprising a tube of flexible relatively soft material having a proximal end and a distal end terminating in a tip, a Doppler crystal at the tip of the tube, and a conductor connected to the Doppler crystal and extending lengthwise of the tube. A connector at the proximal end of the catheter connects the conductor to a source of energy to cause the Doppler crystal to emit pulses at predetermined frequency for measuring the velocity of coronary blood flow. The Doppler crystal is relatively small compared to the diameter of said tube and is so located relative to the tube that the crystal is adapted to assume a position generally at the diametrical center of the coronary artery when the tip of the catheter is inserted therein.