The proton implantation effects on electrical and recombination properties of undoped ZnO were studied. Photoluminescence (PL) spectra measurements showed a very strong decrease in PL intensity in all bands after heavy implantation with 100 keV protons. Three deep electron traps with apparent activation energies of 0.55, 0.75 and 0.9 eV were introduced by proton implantation.