We report a case of hypokalaemic quadriparesis occurring 37 years after a bilateral ureterosigmoidostomy. The history and physical signs as well as cerebrospinal fluid analysis initially led to a diagnosis of Guillain-Barré syndrome. Acidosis and profound hypokalaemia were present and a dramatic improvement occurred after rapid correction of the potassium depletion. The underlying mechanism of potassium depletion which occurs after this mode of urinary diversion are briefly discussed.