In this study, Hasak and Hasmer ewes were used in order to determine the effects of age, year and breed on the conception rate, prolificacy, viability and productivity. The least-squares means for these parameters of all flock were found as follows; 87.27±0.01 %, 117.16±0.01 %, 87.06±0.01 % and 103.34±0.02 %, respectively. In addition, the effects of sex of lamb and birth type on viability were also studied. Except for prolificacy, effects of the age on these parameters were found to be not statistically significant. The maximum prolificacy was obtained with 6-years old ewes. Effect of breed was significant on the prolificacy (P<0.05) and conception rate (P<0.01). With regard to prolificacy, Hasmer ewes were superior to Hasak (120.90 % vs. 113.41 %). The year factor had a significant effect only on the prolificacy (P<0.05). Sex effect on the viability was not significant, but birth type effected viability significantly; single lambs being superior to twin ones.