Nanocrystalline thin films of Al doped ZnO (AI:0-5 at%) with low electrical resistivity and high optical transparency have been grown by pulsed laser deposition. X-ray diffraction patterns showed the presence of hexagonal wurtzite ZnO phase with strong c-axis orientation in all the cases. The c-axis lattice parameter was found to increase with increase in Al doping. The average grain size in the film decreases from similar to 38 to similar to 25 nm with increasing Al concentration from 0 to 5 at%. For a critical doping of 2 at%, the resistivity of the AZO film is minimum (6 x 10(-4) Omega-cm) and the average optical transparency is nearly 85%. The band gap increases with increase in doping which is in accordance to Burstein-Moss shift. A blue shift in the absorption edge of ZnO with increasing Al concentration in the film is noteworthy as it leads to increase in the width of the transmission window. (c) 2006 Published by Elsevier B.V.