Three-dimensional incompressible laminar fluid flow and heat transfer of a heated array of rectangular perforated and solid fins attached on a flat surface are studied numerically. Perforations with rectangular cross section are along the length of bluff plates and their number varies from 1 to 8. A SIMPLE code using control volume approach is developed for solving Navier-Stokes equations with conjugate energy equations for both fluid and solid regions. The second order upwind technique is used for discretization of momentum and energy equations. Computations were performed for a range of Reynolds numbers 100 <= Re-D <= 350, based on fin thickness. Thermal performances and effectiveness as well as friction coefficient of perforated and solid fins are determined and compared. Higher performances for perforated fins are observed and effectiveness increased by increasing number of perforations. Higher reduction of weight of fins due to perforation is another major of utilization of the new type of fins structure. Finally a new correlation is proposed to predict perforated fin effectiveness for the range of computation carried out for the considered fins. (C) 2009 Elsevier Ltd. All rights reserved.