Nephrocalcinosis, i.e. microscopic calcium compounds de-posited in the renal tubules and parenchyma, may be caused by therapy with furosemide or vitamin D. In our study it occurred in 33.3% of patients receiving vitamin D therapy and 15% of patients receiving furosemide. Abdominal ultrasonography is a useful tool for early detection of nephrocalcinosis and saving the kidney by stopping the offending drug.