Abstract: Plastic bottles from a molding machine are transported on a conveyor through a leak testing device where a predetermined number are temporarily stopped in register with overhead reciprocable test heads and with lateral ejectors on one side of the conveyor path. The bottles are supported on the opposite side by a movable side gate which, when a defective bottle is to be ejected, is moved to a clearance position. The test heads are lowered into air tight communication with the mouths of the bottles and a constant volume of pressurized air is discharged into each bottle from a reservoir. The resultant pressure of the bottle-reservoir system is an index of bottle integrity.