The research was carried out to determine efficiency of oestrus synchronization in Chios x Kivircik (F-1) sheep under producers' conditions and the effects of PMSG dose on reproductive performance criteria. Research was conducted with 120 animals. During the mating season, the ewes were divided into 4 groups and 2 groups were administered with sponge + different doses of PMSG (400 and 500 IU), one group was administered only with sponge and one group became the control group. The mean live weight of Chios x Kivircik (F,) sheep was 39 kg, their mean pregnancy rate was 72%, their litter size was 1.36 and the number of weaned lambs was 0.65. When, the variations between mean live weights in ewes were examined by age, it was found to be significant (p<0.01). The effect of PMSG dose on pregnancy rate and litter size was significant (p<0.05).