A series of aluminum doped zinc oxide thin films with different thickness (25-150 nm) were deposited on indium tin oxide coated polyethylene terephthalate substrates by radio frequency magnetron sputtering method at room temperature. The structural, optical and electrical properties of the films were investigated by X-ray Diffractometer, UV-Vis spectrometer and Hall Effect Measurement System. All the obtained films were polycrystalline with a hexagonal structure and a preferred orientation along  direction with the c-axis perpendicular to the substrate surface. The optical energy band gap (E-g) values of the films were found to be in the range from 3.36 to 3.26 eV, and their average optical transmissions were about 75 % in the visible region. The films had excellent electrical properties with the resistivities in the range from 2.78 x 10(-5) to 2.03 x 10(-4) a"broken vertical bar cm, carrier densities more than 3.35 x 10(21) cm(-3) and Hall mobilities between 5.77 and 11.13 cm(2)/V s.