The present study undertakes the deficiency effect of dietary magnesium on bone metabolism and some biochemical parameters in female rats. Experimental diets included control diet (65 mg magnesium / 100 g) and the deficient magnesium (3 mg/100g) diet. Deionized water was supplied for drinking. Forty six albino female rats were divided into two main groups, the first group included 18 adult female rats, divided into 9 control and 9 animals given magnesium deficient diet. The second group included young female rats divided into two groups, the first group was treated from dams،and included 14 young female rats. They were divided into 7 control and 7 magnesium deficient group. The other one was treated at 28 days old and included 14 young female rats, which were divided into 7 control and 7 magnesium deficient group. Blood samples were obtained at specific times from each group for biochemical parameters: magnesium, alkaline phosphatase activity (ALP), albumin, calcium and phosphorus were estimated. At the end of the experimental period, rats were anesthetized and killed. The right femurs were obtained for mineral analysis in bone ash (Ca, Mg). The results of adult female (Mg deficient) group showed a significant decrease in magnesium, ALP activity, albumin, calcium (within normal range). Both young female rat groups showed a significant decrease in magnesium, ALP and albumin compared with control group. The mineral analysis in bone ash showed no significant differences in calcium level where a significant decrease in magnesium level was observed compared with the control groups. It was concluded from this study, that magnesium deficiency could be used for detection of osteoporosis and defect of bone formation in adult and young female rats, respectively.