A numerical investigation of laminar forced convection was performed in a three-dimensional channel with a baffle in the entrance region. The top and bottom watts were subjected to a uniform heat flux heating condition, while the side watts were insulated. The numerical study was conducted using a finite volume approach, and the grid independence was established. Parametric runs were made for Reynolds numbers (Re) of 100-500; Prandtl numbers of 0.7 and 7.0; baffle heights (Bk/Dh) of 0.25, 0.50, and 0.75; and thermal conductivity ratios (K) of 10,100, and 1000. Three-dimensional effects in the flow field were confined to the neighborhood of the baffle, but three-dimensional effects in the temperature field were present in the entire channel In general, separation length upstream of the baffle and recirculation length downstream of the baffle increased with an increase in the flow Reynolds number and baffle height The spanwise averaged Nussett number increased with an increase in the thermal conductivity of the wall. © 1997, Taylor & Francis Group, LLC. All rights reserved.