The current study aims to investigate the effect of different concentrations of sodium dodecyl sulfate (SDS) in tris-egg yolk-based extenders on post-thaw semen characteristics in order to improve freezability and DNA integrity of bull spermatozoa. Semen samples were collected from four adult fertile healthy bulls; Samples were collected weekly from each bull for six successive weeks using an artificial vagina. After initial microscopic evaluation, ejaculates from each bull were diluted in a Tris-based buffer egg yolk extender and cooled to 5C. The Semen extender was supplemented by different concentrations of SDS; 0 (as a control group), 0.25, 0.5, 1 and 1.5 %. Samples were processed for cryopreservation. Frozen straws were thawed in water bath at 37°C for 30 sec and then evaluated for post- thaw motility, viability index, mitochondrial activity, plasma membrane and acrosome integrities. Comet assay was applied to determine the DNA integrity of spermatozoa. SDS at concentrations of 0.25% resulted in the best motility, mitochondrial activity and acrosome, membrane, and DNA integrities of post- thaw bull spermatozoa. Increasing concentration of SDS above 0.25% appeared to have deleterious effect of sperm acrosome, membrane and DNA integrities, Defects in sperm DNA manifested as increased in the percentage of fragmented DNA, DNA content in tail of comet, tail length and Olive tail moment. In conclusion, 0.25% SDS is the optimum concentration for cryopreservation of bull spermatozoa in order to improve freezability and DNA integrity.