Bartter and Gitelman syndromes are salt wasting alkaloses. These inherited conditions are the result of impairment of sodium chloride reabsorption in the loop of Henle (Bartter) or distal tubule (Gitelman). Secondary hyperaldosteronism occurs as a direct result of renal salt wasting resulting in hypokalaemia and metabolic alkalosis. The tubular defects seen mimic those of long-term loop (Bartter) or thiazide (Gitelman) diuretic use and urinary calcium levels and serum magnesium levels can be used to help distinguish them. Molecular genetic testing usually provides a definitive diagnosis. Blood pressure is frequently low or normal (at least until mid-adult life). Treatment of patients with salt-wasting alkaloses involves life-long supplementation with sodium chloride, potassium chloride, and magnesium salts, together with potassium-sparing diuretics and non-steroidal anti-inflammatory drugs.