The heat transfer characteristics of Bingham plastics fluids within concentric annular ducts are analytically studied through the classical finite integral transform technique. In the analysis of the thermal entry region, four types of boundary conditions are adopted and prescribed either at the inner or outer duct wall, and the flow is considered to be laminar and fully developed. Local Nusselt numbers are computed along the channel length with high accuracy for different values of aspect ratios and yield numbers, which are systematically tabulated and graphically presented, Comparisons with previous works in the literature are also performed for typical situations, in order to validate the numerical codes developed in this work, as well as to demonstrate that consistent results were produced.