A nozzle for the treatment of threads is divided in the conveying direction into a conveying part, a compression section and a guiding part. The compression section, for the purpose of forming a yarn plug, includes fixedly arranged radially and axially directed lamellar. The ends of the lamellar which face the guiding part are neither in contact with each other nor with any surrounding parts of the nozzle so that fibers which are located in the gaps between the lamellar, and which radially exit the channel being formed by the lamellar can reach an inlet funnel of the guiding part or a plug guide tube respectively, without colliding with any edges.
