Abstract: Objective To explore the application of furosemide/hydrochlorothiazide load test in clinical classification of Bartter syndrome and Gitelman syndrome and the significance of selecting target genes. Method The clinical features, biomarkers, the furosemide/hydrochlorothiazide load test, and gene detection in 5 patients with Bartter syndrome and Gitelman syndrome were retrospectively analyzed during 2012 to 2014. Results All of those 5 patients were manifested low potassium and metabolic acidosis; basis of renin, angiotensin II, and aldosterone were elevated. The blood pressures were normal. Most of the patients suffered from polydipsia, diuresis, and different degrees of growth retardation. The gene analysis of these 5 patients made the same diagnoses as furosemide/hydrochlorothiazide load test did. Conclusions Furosemide/hydrochlorothiazide load test can make a differentiation of Bartter syndrome from Gitelman syndrome and thus it can guide the selection of targeted gene detection.