For 90 days, eignt buffalo- calves were used to study the effect of fortifying the commonly fed Egyptian rations with manganese sulphate on their health and performance. Throughout the experiment all calves were received two basal rations. Basal ration one, were fed for 15 days and was composed of green barseem, commercial concentrate mixture, and wheat bran. After that the animals received basal ration two, which was composed of barseem hay, commercial concentrate mixture, and green corn. The calves were divided into 3 groups, group one received no supplementation with manganese sulphate, while groups 2 and 3 were received in addition to the basal ration 500 mg and 1000 mg manganese sulphate respectively. During the experiment, body weight gain was recorded and blood samples were collected for the determination of mangan ese, copper, zinc, calcium, phosphorus and magnesium levels in blood serum. The results were as follow: - Body weight gain of calves in different groups did not signifi cantly affected by different manganese supplementation, how ever, a high weight gain was recorded in all groups. - Strong positive correlation was observed between serum manganese and serum copper level in group III, also the same positive correlation was recorded between serum manganese level and that of serum calcium in group III, and between serum manganese and serum magnesium levels in group ll and group III while a negative correlation was recorded between serum level of manganese and phosphorus levels in group III.