Ultra sonographic studies of ovarian activity in postpartum anestrous Sahiwal Cows. A total no. of 14 anestrus Sahiwal cows with normal parturition of more than 65 days after parturition were procured for present study from Bull Mother Experimental Farm (B.M.E.F.), College of Veterinary Sci. & A.H., Anjora, Durg. These animals were randomly divided into two groups. Animals (n = 7) of control group were given to the normal saline and animals (n=7) of treatment group were given to the injection GnRH @ 10 µgm intramuscularly on day 0. The animals in both groups were monitored at three days’ interval for 24 days i.e. day 0, 3, 6, 9, 12, 15, 18, 21 & 24 days using trans rectal ultrasonography (5-7.5 MHz) for development of ovarian follicles. Significantly higher number of animals came in estrus (57.14% Vs. 28.57% (P < 0.05) in treatment than control group. Significantly (P < 0.05) larger follicles were observed on day 3, 12 and 24 The serum progesterone level was higher on day 0, 11 and 22 in treatment group. However, the difference was statistically non-significant.