Abstract: Based on the boundary layer theory and the assumption that the torque by the wall of an agitated vessel is approximately equal to that of the rotating impeller a method to calculate the apparent viscosity of non-Newtonian fluids within the resistant layer of heat transfer in agitated vessel has been proposed. By incorporating this method to the Yuji-Sano s correlation, an unified correlation of heat transfer coefficient for both the Newtonian and non-Newtonian fluids in agitated vessels equipped with different types of impellers is obtained as follows: