In two visualization experiments in water, Gyr and Mu¨ller1showed that the addition of dilute polymer solutions changes the pattern of the flow structures near the wall. They observed a thickening of the viscous sublayer and of the buffer zone, as well as a stabilization of the shear waves in the direction of flow connected with an increase in the formation of transverse vortices. This observation is related to the burst cycle mechanism as described by Offen and Kline.2Based upon their burst mechanism a hypothesis is proposed that the drag reduction is the result of a higher alignment of the wall near separation vortices. Such a stabilization of the local pattern would produce a higher number of enrolled vortices, which means more elements of larger coherent motion. At the same time it would reduce the chaotic redistribution in the velocity field. The hypothesis is in good agreement with the observation of higher turbulent intensityu′ in the direction of flow in the buffer zone. To describe this higher stabilization it is proposed to use a constitutive relation of the form, &sgr;=2&mgr;[E+&Vthgr;xˆxˆ (xˆExˆ)] which is based on the concept that the polymer molecules are elongated in the direction of flow (x⁁) and can support strain forces in this direction.3To get an idea of the stabilization process the stability of a plane Poiseuille flow is demonstrated for a fluid with such an anisotropic viscosity, although for a complete investigation at least a two‐dimensional flow system should have been taken into consideration. (The full paper is published in Ref. 4.)