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The successful genetic selection for higher milk production caused a dramatic decline in the reproductive performance of dairy cows all over the world during the last decades.Achievement of optimum herd reproductive performance (calving interval of 12 or 13 months with the first calf born at 24 months of age) requires concentrated management activities especially during the first 100 days following calving.The following management activities are needed to pursue during the early postpartum period to reach or approach the optimal reproductive performance such as careful surveillance and assistance at calving, prevention of periparturient metabolic diseases, early diagnosis and treatment of post parturient uterine diseases, accurate detection of oestrus, correct timing of insemination, reducing the effect of heat stress and early pregnancy diagnosis.Among these main activities only early diagnosis, and treatment of periparturient metabolic diseases and their effects on reproductive performance and milk production are discussed.Fertility in dairy cows reflects the cumulative influence of metabolic, endocrine, and postpartum health components.Energy imbalance seems to be one of the most important factors, but the complex interactions of the aforementioned factors can be considered in order to be able to improve fertility, at the same timebody condition score (BCS), glucose, non-esterified fatty acid (NEFA), insulin-like growth factor-1 (IGF-1), leptin concentration from calving to AI cannot explain the low fertility rate.Cows should be challenge-fed during the dry-off period and early lactation to prevent the incidence of metabolic disorders of the puerperal period such as milk fever, acidosis, ketosis and fat cow syndrome.These diseases can increase the incidence of reproductive diseases and reduce reproductive performance.Prevention is more preferable than treatment and requires close attention to nutrition and management.The maintenance of good condition at calving and the provision of a high-density energy diet that does not produce a fatty liver in early lactation are also very important to minimize the detrimental effect of NEB on the return of oestrous cycle after calving.