The purpose of estrus synchronization is to manipulate the bovine estrus cycle and achieve a result were the majority of animals on a farm exhibits standing heat in a short period of time. It is a very effective method to increase the proportion of animals that are bred at the beginning of the breeding season. The use of estrus synchronization in cattle to control follicular development and ovulation has been shown to be practical and easy to perform by both veterinarians and farm staff. The newer protocols utilizing fixed-TAI without the need for detecting estrus have decreased the accuracy in estrus detection and the handling of animals. Treatments including GnRH, PGF2α and progesterone-releasing devices have provided for fixed-TAI in beef and dairy cattle and the use of PRID and eCG have been especially useful in increasing PR in cows experiencing PPA. Other methods such as the 5-day co-synch and MGA feeding have also shown to be effective in inducing estrus in non-cycling heifers. Even though estrus synchronization programs are a useful tool in the reproductive management of a cow herd it is necessary to maintain proper levels of nutrition, BCS and health for the protocols to be effective. If they are not maintained properly, the programs are likely to fail.