The efficacy of Clindamycin and Monensin were evaluated in the prevention of oocyst shedding of kittens with Toxoplasma gondii (Tehran strain). In this study, 28 healthy kittens aged 1.5 – 2 months old divided randomly into 4 groups of seven. In group 1, Kittens were fed with the infected brain tissues of mice, all of seven kittens (100 %), shed oocyst, nearly 1 week after infection, which lasted for 8 to 9 days. In group 2, kittens were fed with infected brain tissues of mice and Clindamycin at dose of 20 mg/kg from day -3 to + 21 after infections, none of seven kittens, shed any oocyst. In group 3, kittens were fed with Clindamycin at dose of 10 mg/kg, same as group 2, two of 7 kittens (28/6%), began to shed oocyst from day 11 to 18 after infection. Kittens of group 4 that were fed with Monensin at dose of 0.02 % incorporated in dry food did not shed any oocyst. Data analysis revealed that Clindamycin 20mg/kg and Monensin 0.02% had a 100% inhibitory effect against Toxoplasma gondii (Tehran strain). No adverse reactions were observed during the experimental period.