One patient with Bartter-syndrome and two patients with pseudo-Bartter-syndrome in abuse of laxatives and diuretics, respectively, were examined clinically and biochemically. The causes of the severe disturbances of the electrolyte metabolism are demonstrated. The differential diagnosis between Bartter- and pseudo-Bartter-syndrome is discussed, exact investigations of electrolyte balance of intake and output are decisive. In consequent therapy with prostaglandin inhibitors (indomethacin), aldosterone antagonists (verospirone) and oral electrolyte supply the prognosis of the Bartter-syndrome is favourable. Little successful is the treatment of the pseudo-Bartter-syndrome. On account of the severe psychic disturbance of the personality a renunciation of laxatives and diuretics, respectively, is frequently not to be achieved.