Abstract: Blood minerals level in relation to various stages of estrous was determined in 35 Friesian and jersey cows. The experimental animals were divided in to following 4 groups 1. Friesian cows non cyclic. 2. Friesian cows repeat breeder 3. Jersey cows noncyclic 4. Jersey cows repeat breeder. Blood serum was analyzed for calcium, In organic phosphorus and magnesium. The mean values of calcium 1.96, 2.68, 1.89 and 2.67 m mols-1 lit and of phosphorus were 1.46, 1.57, 1.42 and 1.50 m mols-1 lit in four above groups respectively. The mean concentration of magnesium was 0.80, 1.03, 0.84 and 0.99 m mols-1 lit respectively. The concentration of calcium and inorganic phosphorus was significantly higher in repeat breeder (2, 4 groups) than in non cyclic cows (1, 3 group). The calcium and phosphorus ratio (Ca : P) was significantly wider \lower 1.34:1, 1.33:1 in non cyclic Friesian and Jersey cows than 1.70:1, 1.78:1 in repeat breeder Friesian and. Jersey cows respectively.