This study aimed to evaluate the effect of exogenous multiple insulin injections on ovarian and estrus activity, and pregnancy rate in repeat breeder Friesian cows. Cows (n=12) in heat (Day 0) were divided into three groups. Cows were subcutaneous injected with 0.2 IU insulin/kg LBW on day 9 (G1), 8, 9 and 10 (G2), or 7, 8, 9, 10 and 11 (G3) of the normal estrous cycle. In G1, G2 and G3, cows were i.m. injected with 3 ml PGF2α on day 12. All treated cows in the next heat within 48-72 h post- PGF2α treatment were artificially inseminated with proven fertile semen. Based on overall mean, results showed that follicular number was the highest in G1 and the lowest in G3 (P<0.05). Follicular diameter was higher (P<0.05) in G3 than in G1. Largest follicles diameter was not affected. Diameter of CL was higher (P<0.05) in G2 and G3 than in G1. Serum P4 concentration was higher (P<0.05) in G2 and G3 than in G1. Serum P4 concentration was highest in G3. Pregnancy rate was higher (P<0.05) in G3 (75%,) than in G1 and G3 (50%). The administration of multiple injections of insulin at days 7, 8, 9, 10 and 11, followed by 3 ml PGF2α on day 12 from initiation of normal estrous cycle improved ovarian and estrous activity, and pregnancy rate of repeat breeders Friesian cows.