The non-isothermal laminar flow of the Bingham non-Newtonian fluid through a sudden pipe expansion with a solid center-body placed upstream of the expansion plane, is investigated. The governing equations of conservation of mass, momentum and energy are solved using the finite-difference numerical technique. The effects of center-body-blockage-ratio, non-dimensional yield stress, Reynolds number, Prandtl number and Brinkman number on the flow and heat transfer characteristics are studied. The obtained results indicate the complex nature of the present viscoplastic flow and heat transfer problem and reveal new features not encountered in the case of Newtonian fluids. (C) 2000 Elsevier Science Ltd. All rights reserved.