The present paper shows results of laboratory measurements carried out to study effect of perforations on the cooling of cylinders under forced convection. Measurements were carried out for Reynold's numbers between 2000 and 15,000. Results indicate that the presence of holes and their orientation relative to air flux have a significant effect on the cooling process. Nusselt numbers have been found to increase as much as 20% as compared to a corresponding smooth cylinder. (C) 2007 Elsevier Ltd. All rights reserved.