The aim of this study was to investigate the post-thaw motility and morphological defect rates of cat semen frozen with various extenders, and pregnancy rates aft er intrauterine insemination (IUI). Cats, 2 males and 14 queens, 2 to 3 years of age, and under the same managemental conditions were used. Semen was collected by means of an electro-ejaculator under general anesthesia. Based on spermatological traits, semen samples presumed suitable for freezing were extended with either tris-fructose-citric acid (EY-TFC) containing 20% egg yolk, or skimmed milk-glucose-taurine (EY-SMGT) containing 10% egg yolk extender, and frozen in 0.25 mL straws. For the extenders, post-thaw motility and morphological abnormality values were found to be efficient for IUI and no statistical significance was observed between the values of the extender groups. To achieve ovulation, queens showing behavioral estrus received 250 IU of hCG via IM route, 30 h prior to IUI. Under general anesthesia, queens were laparatomised on the medial line and the left and right uterine horn were taken out. Into both uterine horns, 2 straws containing 25 x 106 sperm each were thawed at 37 degrees C for 30 s and equally injected. Pregnancy was diagnosed using an ultrasonography device on the 19th day aft er IUI by detecting the embryonic vesicles. Of the 3 EY-TFC group queens found to be pregnant, 1 aborted and other 2 had early embryonic death (EED); the pregnancy rate was 42.90%. In a queen in the EY-SMGT group, no ovulation took place aft er the hCG injection. In 2 of the queens found to be pregnant in this group, EED occurred and the pregnancy rate was 33.30%. In conclusion, cat semen extended and frozen with EY-TFC and EY-SMGT extenders was found to be successful in post-thaw motility and morphological defect rates. Therefore, surgical IUI may be more effective for feline AI using frozen semen rather than intravaginal insemination.