Reproductive capabilities are significant economic characteristics and they are given special attention and strives to maintain at a satisfactory level or even improve by different zootechnical measures. Reproduction in Holstein cows is an introduction to production and are indirectly linked, and better reproductive characteristics in cows also give positive economic effects. Significant reproductive characteristics are the index of insemination and the success of insemination after calving. The research work was based on proving the effect of residual placenta and its retention on the mentioned reproductive properties. The first group of cows X1 consisted of cows with normal calves and numbered 34 cows, and were characterized by on time plunged placenta, with an average index of insemination of 1.2. The insemination index in the group of cows X2 containing 20 cows with residual placenta, and where reteniting of placenta was up to 30 hours after calving, was 2.1. The largest oscillation index had a group of cows X3 that counted 14 heads, where the placenta retention was made after 30 hours from the calving moment with a 4.86 index. Detailed analysis of the insemination index showed the data for the success rate of insemination, for the group X1 from the first attempt was 79.41% and from the second was 20.59%. Group X2 has an insemination performance for the first attempt of 45.0%, the second attempt was 30.0%, the third 10.0% and the fourth was 15.0%. Cows that have placental retention after 30 hours of calving, X3, the success rate of insemination is very low, and for the first attempt it was 14.3%, the second and the third to 7.15% while for the fourth and subsequent attempts was 50.0%. The best reproductive indicators had a group of cows with normal calves and calves removed on time.
KEY WORDS: index of insemination, placenta retention, success of fertilization.