Metabolic studies of calcium, phosphorus, and nitrogen in children with moderate to severe idiopathic scoliosis have been carried out. The findings demonstrated no clear-cut abnormality in mineral metabolism, but did show a serious disturbance in catabolism of protein with excessive wastage of nitrogen through the urine. The metabolic error also appears to involve derivatives of sulphur-containing amino acids. The scoliotic children tended to excrete a larger number of essential amino acids than did normal children of the same age range.