Abstract: An eyelet buttonhole sewing machine has a suction device between the throat plate and the wedge-shaped knife of the buttonhole cutting device. The suction device includes a suction tube and is connected to a vacuum generator, for instance an ejector nozzle or a transvector nozzle. The looper thread is brought near the suction device by a thread puller. When the looper thread is cut by the thread cutting device at the end of the sewing process, suction is applied to the suction tube, pulling the end of the looper thread into the opening of the suction tube. In this way, the looper-thread end assumes a well defined position in which it is disposed for being completely covered by the corresponding welt of the following buttonhole to be sewn. With the suction device and thread puller operating as described, it is no longer necessary to clean the buttonhole by cutting off the end of the looper thread.