Toxoplasmosis is an important cause of abortion and stillbirth in sheep on a worldwide basis. In the present study, the role of Toxoplasma gondii in inducing abortion in sheep of the Mashhad area of Iran was addressed using serological and parasitological methods. In total, 325 aborted ovine fetuses were collected between 2006 and 2008 during lambing season. Thoracic and abdominal fluids of aborted fetus were serologically investigated with a T. gondii-IFAT. Antibody titers equal to or greater than 1∶20 were detected in 17 (5.2%) of ovine fetuses. Processed brain samples of seropositive ovine fetuses were intraperitoneally inoculated into mice for isolation of T. gondii. The process yielded a single T. gondii isolate that remained avirulant for mice after several passages. The results document that T. gondii is among the important causes of ovine abortion in Iran.