Heating of non-Newtonian fluids is of particular importance to food processing systems. However, excessive pumping demand generally precludes development of turbulence in tubular arrangements. So, laminar flow is all that can be developed in heat transfer equipment handling non-Newtonian materials. The paper presents a theoretical model of heat transfer, which is dependent only on the flow behaviour index of the fluid. Increase in flow behaviour index produces a lower convective heat transfer coefficient and for real non-Newtonian fluids Nusselt＇s number approaches a fixed value corresponding to a flow behaviour index of 4.