In the light of published observations attention is called to the various forms of renal tubular acidosis (RTA), its etiology, pathologic significance, excretion of an "alkaline-persistent" urine in the presence of hyperchloremic acidosis, and to the possible consequences: nephrocalcinosis and renal calculosis. The frequency of incomplete RTA of various causes in calculosis is pointed out. The patient material of the authors and the results of phosphate therapy are presented, stressing the importance of alkalizing therapy and its prophylactic value.