The influence of quantum size effect on the transport properties of ultrathin Cu and Fe films in the thickness range between 1 and 32 monolayers is studied by solving the linearized Boltzmann equation in the relaxation-time approximation using ab initio calculations within the framework of spin density functional theory. A strong manifestation of quantum confinement is found in the density of states. However, the plasma frequency shows a smooth or oscillating behavior for different film orientations. The results are in qualitative agreement to infrared-absorption experiments at Cu(111), Fe(001), and Fe (111) films. (C) 2007 Elsevier B.V. All rights reserved.