In this trial, the efficacy of Gonadotropin Releasing Hormone (Factrel^R), administrated at the time of mating, on the pregnancy rate of dairy cows were studied.

Sixty- nine cows were used as materials. Animals were divided in to two• groups and 25µg Factrel were injected to the first group of 33 aniınals and Placebo to the second group of 36 animals.

Rectal exploration was performe.d. for estrous controls and pregnancy examinations were done post- mating 19- 21 and 60 days respectively.

The pregnancy rates of Factrel injected group (81.81 %) were found higher than the controls (63.88%). The value was found significimtly higher between the two groups (P :<; 0.01).

The results were evaluated among the age groups. The differences in the pregnancy ra te were found higher in younger cows ( < 5 ages).

There was a markeel improvement in the fertility rate in hormone treated cows after the relatively short interval ( < 60 days) between calving and mating.

As a conclusion, the pregnancy rates could be improved with GnRH injections at the time of mating in the early postpartum cows.