High-quality Gallium-doped zinc oxide (ZnO:Ga) films have been prepared on epi-GaN/sapphire (0001) substrates by the metalorganic chemical vapour deposition (MOCVD) method. The relative amount of gallium doping was varied from 0 to 8% (atomic ratio). The structural, electrical and optical properties of the ZnO:Ga films have been investigated in detail, as a function of Ga content. All the prepared samples have the wurtzite structure of pure ZnO with a strong (0002) preferred orientation. The microstructure for the surface of films was markedly influenced by the amount of Ga doping. The resistivity decreases continuously with adding Ga content and reaches to the value of 8.4×10-3 Ω•cm at 8%. The average transmittance for the deposited ZnO:Ga samples in the visible range was over 75%.