Carbohydrate metabolism was studied in a family (a mother and her three sons) suffering from hypokalemic periodic paralysis. The levels of insulin, growth hormone, and 11-oxycorticosteroid were found to be normal. Glucose load did not induce hypokalemia, nor did it cause muscle weakness. Electromyographic examinations performed in three of the patients showed a paucity of functioning motor units in each patient. The disturbed EMG improved considerably during acetazolamide treatment and in response to an ammonium chloride load.