The effect of three levels of protein on the utilization of magnesium, calcium, manganese, iron, copper, zinc, sodium and potassium was studied in preadolescent girls. Minerals were determined in excreta and food following a wet ash by absorption spectrophotometric procedures. The minerals magnesium, calcium and manganese were better utilized with low protein intakes. The utilization of copper, zinc, and sodium were enhanced on moderate protein intakes. A high protein diet was detrimental to the utilization of these minerals when present in low levels but enhanced the utilization of copper, and did not affect sodium utilization adversely. The effect of protein on iron absorption was not clear. Protein level did not affect the potassium utilization. / Master of Science