1. Metabolic balance studies in two cases of the Fanconi syndrome are presented.

2. The actions of sodium bicarbonate and calciferol on the calcium and phosphorus balance were observed separately in the two cases.

3. The results show that sodium bicarbonate alone corrects acidosis and decreases the loss of calcium in the urine.

4. Calciferol in high dosage will increase intestinal absorption of calcium and phosphorus, but the urine calcium excretion then increases and vitamin D alone does not, therefore, give a positive balance adequate for complete healing and normal growth.

5. Alkalies and calciferol together put these cases into strongly positive calcium and phosphorus balance and promote healing of rickets, osteomalacia and pseudo-fractures.

6. Large doses of sodium bicarbonate in tablet form correct acidosis, do not adversely affect intestinal absorption of calcium, and facilitate accurate dosage and convenient administration.

7. Alkali therapy may lower serum potassium and precipitate symptoms of hypokalaemia in potassium-losing patients. This is thought to have been the cause of symptoms in several cases reported in the literature.