Abstract: Nozzle assemblies for texturing one or several yarns consisting of a plurality of endless synthetic filaments are described wherein the yarn passes through a whirling chamber, fed laterally through at least one oblique bore with compressed air, into a nozzle with a spherical guide element located in the divergent part of the nozzle so as to define therewith an annular slot in which the spreading air stream from the whirling chamber is accelerated. The whirls and loops formed in the individual filaments are subjected to increased whirling by the deflection of the air stream by the guide element, which is mounted for both axial and lateral adjustment in the nozzle. The guide element may present a hemispherical surface towards the whirling chamber or, alternatively, a frusto-spherical surface with a central concavity. The yarn is withdrawn laterally from the air stream beyond the nozzle.