A method is descr. for placing permanent polyethylene catheters into the pulmonary artery or vein of dogs without resort to major surgery. These tubes are introduced through the external jugular vein or common carotid artery, resp. The emerging ends of these tubes are protected by a collar around the neck. Dogs have been kept as long as 2 mos. in perfect health with tubes in the pulmonary artery for sampling and measuring pressures. The pulmonary vein catheters, however, cause considerable local trauma and animals succumb within 10 days after placement of the tube.