This study reports the results of an experimental and numerical investigation of mixed convection from a heat generating element in a ventilated cavity. Experiments were carried out for heaters of two different sizes, located centrally in a parallelepiped that has an air inlet and an outlet port. An induced fan at the outlet is used to create a flow, thereby facilitating studies in the complete mixed convection regime. After a detailed parametric study, correlations have been developed for the average Nusselt number and the maximum dimensionless temperature occurring in the heat generating element. Experiments have been backed up by a numerical analysis of fluid flow and heat transfer for a geometry that corresponds exactly to the one used for the experiments. The good agreement between the experiments and the numerical results confirms the adequacy of the two dimensional approximation and the turbulence closure model employed. Based on the numerical results, the position of the heat source was changed in order to improve the heat transfer performance and the experiments were repeated for this new position. Hence, a combined experimental and numerical investigation will significantly reduce the effort required to optimize the thermal performance in problems of this class. © 2007 Elsevier Inc. All rights reserved.