Abstract: A device for inserting a catheter tube in a vein or the like. The needle portion of the device is slotted along one position and partially along another position so that the needle after withdrawal from the body may be separated from the tube by withdrawing the tube through the continuous slot. The adapter portion of the device attached to the needle may be rigid or non-rigid. If it is rigid, it is preferably tapered toward the rear. The continuous slot may be tapered or non-tapered. A novel tapered catheter with a slot at the narrow end may be employed with the insertion device.