This study examined the effects of Beta-carotene (?C) injections before estrus synchronization with PGF 2? on fertility parameters in cows. A total of 124 postpartum (pp) cows were used. In GI (n=25), ?C (Carofertin®, 0.4 mg/kgBW, i.m.) was injected on d 15 and 45 pp. In GII (n=25), ?C was administered on d 15 pp. In GIII (n=25), ?C was administered on d 45 pp. In GIV (n=25), ?C was injected on d 35 and 45 pp. GV (n=24) was set aside as a control group. All animals received PGF 2? (Iliren®, 0.0015 mg/kgBW, i.m.) on d 50 and 61 pp. Blood samples were collected on d 15, 48 and three days after each ?C injection. The overall pregnancy rate was determined to be higher in GI (100%) and GIV (88.0%) than GV (70.8%) (P