The aim of the present study was to elucidate the effect of thiourea on motility and viability of chilled-stored and frozen-thawed goat spermatozoa. Five male Baladi goats were used in three experiments during this work. Three different Concentrations (10,50 and 100 mg %) of thiourea were added to semen extenders before processing. Tris-based egg yolk and Tris-egg yolk free extenders were used for chilled-storage of spermatozoa in the first and second experiments, respectively. In the third experiment, motility and viability of frozen-thawed goat semen were evaluated after inclusion of 50 mg% thiourea in the extender. In vitro augmentation of semen extender with 50 mg % thiourea exerted a pronounced improvement in incubated and post-thawed sperm motility percentages and viability indices of goat spermatozoa either in presence or absence of egg yolk. It is concluded that Tris-egg yolk free extenders could be used in presence of 50 mg % thiourea for both incubation and preservation goat semen.