We report the case of an 8-yr-old girl with short stature. Her height was -2.65 SD and blood examination revealed hypokalemia (2.9 mEq/l), hypomagnesaemia, hypocalsiuria (Ca/Cr=0.0039) and metabolic alkalosis (pH 7.454, HCO₃^- 24.9 mmol/l). For differential diagnosis between Gitelman's syndrome (GS) and Bartter syndrome (BS), we performed the loop diuretic furosemide (FUR) test and hydrochlorothiazide (HCT) double dose (2 and 4 mg/kg) test. Even the higher dose of HCT induced significantly lower increase of urinary Na and Cl excretions than the FUR. Growth hormone (GH) secretion tests (insulin and arginine) revealed GH deficiency. In addition to growth hormone injection, administration of Mg and spironolactone was started. After the replacement therapy started, the girl's height gain was improved (9.7 cm/yr) and her serum potassium became within the reference range. One year after GH replacement therapy was performed and GH replacement therapy was discontinued for two months, and GH secretion tests (insulin and arginine) showed GH deficiency again. We discussed previous reports of the clinical signs and test results of GS with regard to the relation between hypokalemia, hypomagnesemia and short stature.