The problems of laminar and turbulent heat transfer in time-independent non-Newtonian fluids are under discussion. It is shown that in the laminar flow regime of temperature-independent fluids without internal heat sources the shear dependence of viscosity slightly affects the heat transfer. The effect of viscous dissipation and temperature-dependent viscosity on heat transfer is evaluated. It is shown that the turbulent heat transfer in non -elastic fluids may be calculated by standard formulas using the wall shear viscosity values for the Reynolds and Prandtl numbers. The turbulent heat transfer in drag-reduction flows is analyzed.