Toxoplasma gondii is an apicomplexan parasite that infects human and almost all warm-blooded animals. The life cycle of the parasite includes an asexual reproduction in intermediate hosts (Mammals and birds) and a sexual reproduction in definitive hosts (Felidae). Cats are both the intermediate and the definitive host for T. gondii. The aim of this study was to investigate anti-T. gondii antibodies in cats by using an immunoblot method based on a major surface antigen; SAG1. Six sero-negative kittens were infected intra-peritoneally by Rh strain of T. gondii. Serum samples were collected and evaluated for the presence of IgG antibodies by using two techniques; immunoblotting and indirect fluorescent antibody test (IFAT).SAG1 based immunoblotting was able to detect anti-T. gondii antibodies at least eight days after infection. Comparative evaluation showed that this method is as sensitive as IFAT to diagnose T. gondii infection in cats.