Flow behavior of a 3% solution of polyisobutylene (Vistanex L‐100) dissolved in decalin was studied in helical flow between concentric cylinders. Shear rate in the fluid ranged between approximately 30 and200 sec−1.A flow visualization technique was developed which permitted quantitative measurement of velocity profiles in the helical flow field. Results indicate that the correspondence between helical flow and Poiseuille flow which is predicted for simple fluids in viscometric flows is in fact observed to a close approximation. One concludes that the spatial variation of flow direction which exists in helical flow does not have an important effect on the flow of polyisobutylene solution under conditions studied in these experiments, a result consistent with the theory of simple fluids. Velocity profile measurements at two axial positions in the helical flow field indicate that a fully developed velocity profile was readily established.