Abstract: The flow pattern and velocity distribution for the flow of highly viscous fluid in an agitated vessel with an anchor impeller were studied by means ofstreak photography using selective illumination of polystyrene pearls as tracer particles. Equations for velocity distribution, shear rate r and energy dissipation function Φ, were obtained by using the least square method. The shear rate r in the vicinity of the vessel wall and the Metzner constant ks, were compared with the shear rate averaged over the vessel and the parameter C3 of agitator performance, respectively, that ks and C3 reflect mainly the mean shear rate in the high shear area and the average shear rate over the vessel, respectively, and that, for a uniform shear field, C3 is equal to ks. The per-unit-volume parameter v may be used to characterize the shear rate distribution. The variation of flow pattern and velocity distribution with Reynolds number was also studied. The flow pattern was shown to be symmetrical at low Reynolds number, but asymmetrical at high Reynolds number.