The abuse of laxatives and a prolonged treatment with diuretics has to be brought into consideration as the most common cause for renal or intestinal loss of potassium. Besides characteristical alterations at the E.C.G. and besides intestinal disturbances there do occur again and again acute, life-threatening aspects of cases connected with tetraplegias and a respiratory failure. By means of 3 cases from our hospital and 27 casuistics in literature symptomatology and dynamic in the development of hypokaliemia is discussed. The mean of potassium in the serum of the 16 patients, those having quadriplegias, ran up to 1,7 mval/l (range 1,4-2,5). Paralysis develops peracutely in 4 of the cases within hours and in 12 of the cases within days. In the anamnesis symptoms of adynamia could be traced with nearly every patient. A functional psychosis (reversible physically founded psychosis) couldn't be detected in any of the cases. With the help of a administration of potassium one could achieve a total retrogression of the symptoms. Besides this a normalisation of the acide-base equilibrium is required because of a metabolic alkalosis, detectable in most of the cases.