This paper describes the preparation conditions of undoped and aluminum-doped zinc oxide (ZnO, ZnO/Al) films by a screen printing technique. The structural, morphological and electrical properties of the deposited films were investigated. X-Ray diffraction pattern analysis shows that screen printed undoped and aluminum-doped zinc oxide are polycrystalline. Scanning electron microscopy (SEM) of ZnO shows that the obtained ZnO films are granular and porous. The roughness (sigma) of the films was found to be in the range 1000-2000 Angstrom, depending on fabrication parameters. The electrical behavior of ZnO films under different storage conditions was studied. We show qualitatively that the resistance of ZnO films depends on oxygen and water vapor pressures. We have measured the variation of the electrical resistance at the 300-830 It temperature range, and three activation energies corresponding to donor levels were determined.