Two blood samples, 8 days apart were taken from 150 Balouchi ewes being in their 3-5 years of age and serum progesterone concentrations were determined. One hundred and twenty five ewes that had lower progesterone concentrations have been chosen and in a completely randomized design were assigned into 5 groups of, 600 (n=26), 500 (n=25), 400 (n=24), 300 (n=26) and zero (n=24). Groups were separated just by a physical barrier. Twenty days after the second blood sampling, CIDR-G insert was applied into the vagina of all the ewes and after 12 days, inserts were removed. PMSG was injected IM immediately after CIDR removal in the rate of 600, 500, 400, 300 IU into ewes of the 600, 500, 400, 300 groups, respectively. Ewes in the zero group received an injection of normal saline solution only. One ram per each 5 ewes, were introduced into the flock the same day until a week later when they were separated from ewes. Ram effect was abolished by rotating them in the groups regularly. Ewes were monitored, and in case of return to estrus, were put together with ram again. On day 50± 5, after mating begun, all the ewes were checked by ultrasound for pregnancy. In case of getting negative pregnancy results and returned into estrus and having second mating, ewes were checked 50± 5 days after second mating. Results showed that multiple birth and lambing rate was higher in PMSG injected ewes than the zero group (P<0.05). Similarly, 600 group had the highest multiple births and 400 group had the highest lambing rate among the firs 4 groups (P<0.05). There were no significant relationship between level of PMSG injection and multiple births (P>0.05). Zero group had the lowest and 400 group had the highest total number of lambs and delivered ewes (P<0.05). In conclusion, use of CIDR together with PMSG in anestrus Balouchi ewes can induce and synchronize estrus and increases multiple births. Although, there were no significant difference among the PMSG injected ewes in multiple births but 400 group had the highest score in this respect.

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