A self-occluding catheter includes a body portion for connection to extracorporeal equipment. An elongated tubular extension is provided for insertion into a body cavity. The body portion includes a resiliently biased spool supported therein which is slidable between an open and a closed position for alternately permitting and stopping the flow of blood through the catheter during a given medical procedure. The biasing device for resilient biasing the spool preferably comprises one or more magnets fixed within the body portion which generate a magnetic force for urging the magnetically polarized spool to its closed position.