Abstract: Retained Placenta (RP) may result from a number of factors, such as abortion, forced labor, delayed gestation, early parturition, uterine atony, infections and seasonal and hormonal disorders. In addition, it is well known that deficiencies of some vitamins and minerals induce or predispose animals to RP. The objective of the present study was to investigate the between serum concentrations vitamin A, β-carotene, calcium and phosphorus and the development of RP in cows. The 25 cows were retained placenta; to wit they have not excreted their placenta after parturition. The 20 others have excreted their placenta normally after parturition. Blood samples were obtained from all understudying animals from tail vein by venoject. Samples were centrifuged and sera were prepared and amounts of vitamin A, β-carotene, calcium and phosphorus were measured. Data showed that there is no significant difference among vitamin A and β-carotene between two groups (p>0.05). While revealed that there is a significant difference in mean value of Ca and P among two groups.