Ninety two prim Holstein cows, from different dairy herds, were randomly assigned to progestin protocols (PRID or Norgestomet) or prostaglandin's, to synchronise estrous, according to the most used protocols in Algeria, in order to compare their efficiency on our dairy cattle. All cows were between day 60 and 120 post-partum at the beginning of the experiments, and at a score body condition between      2 and 3,5. The follicular diameters were not significantly different between treatments, whereas ovulations were observed around 15mm of diameter. Results of estrous synchronisation were very different between treatments; treatment with the Intra Vaginal Device (PRID) provided better rates of estrous expression (72,73% and 87,5%) and better ovulations rates (81,82% and 75%) about 96h post treatment. An intermediate rate was observed with Norgestomet protocols (66,67%; 40% and 42,86%) of animals in estrous, and (77,78%; 80% and          57,14%) of ovulations. Bet, a lesser rate was observed with PGF2a protocol (20 and 25%) of estrous expression, rate of animals with retained corpus luteum, was very high and began to decline at 72h after the second injection. In this study, some animals ovulated without expression of  heat; the highest rate (60% and 75%) was noted with prostaglandin's protocols, the intermediate results were observed with Norgestomet protocol (22,22%; 40% and 14,29%), and the lesser rate was noted  with the PRID protocol (9,09% and 0%).