Repeat breeding syndrome in the cow is indicated by normal clinical health and estrous cycle, however, by 3 to 4 or more natural mating by bull and sperm insemination per each pregnancy. In the big farms with artificial insemination, there are several problems in estrous detection, insemination time and pregnant cows breeding which affect repeat breeding syndrome and infertility within the herd. Because of several reasons of repeat breeding syndrome among the cattle and herds, detection and treatment of repeat breeding syndrome needs the abundant knowledge and information. By increment in the herd size, the occurrence of repeat breeder syndrome in the cows also increases. The etiology of repeat breeding syndrome due to the multiple genetic and environmental factors is usually difficult. External and internal factors which commonly overlap together and thud they cause the difficult primary detection of the repeat breeding syndrome. The common reasons of the repeat breeding syndrome are including endocrine disorders, malnutrition and infectious agents. Increment of the calving interval causes increase in the farm costs and reproductive performance. Therefore, the diagnosis of the probable reasons of repeat breeding syndrome and resolving them, protect economic losses and improving herd reproductive performance.