A combined electrocoagulator-suction instrument useful for coagulating bleeding capillaries and veins within a surgical field and for sucking out blood and other liquids from the field either during, before or after the coagulation procedure. An elongate body of electrically non-conductive material is formed with a main flow passage terminating at one end of the body in a nipple for connecting the passage to a vacuum source. A second passage through the body receives an electrical conductor connected to an electro-surgical generator, the end of the conductor passing through the second passage and having its bared end bent back to extend into the interior of the first passage. An open ended metal tube has one end formed to be inserted into the main passage at the end opposite to said nipple, the tube being mechanically seated within the passage in electrical contact with the bared wire end. An electrically non-conductive sheath surrounds all of the exposed surface of the tube with the exception of a short section at the opposite end or tip. A branch passage extends through the wall of the body to communicate with the main passage at a location intermediate the ends of the main passage, the opposite end of the branch passage opening at the exterior of the body at a vent opening which can be fully or partially covered by the surgeon's finger to regulate the degree of suction within the main flow passage. The vent opening is offset from the location at which the branch passage communicates with the main passage in an upstream direction with respect to the direction of flow of fluid through the main passage.