During the past two years 2 patients suffering from chronic nephritis have had several admissions to the wards of the Massachusetts General Hospital, each having one admission to the neurologic service because of muscular weakness. The first patient on his original admission to the medical service was diagnosed as having chronic nephritis, and his next admission was to the neurologic service for severe generalized muscular weakness. The second patient was admitted originally to the neurologic service complaining of periodic attacks of weakness and stiffness of the extremities. The fact that significant kidney damage was present was not discovered until a phenolsulfonphthalein urinary excretion test was done several days later. Disorders of the electrolyte balance in the blood are often manifest by symptoms pertaining to the skeletal musculature. Thus in Addison's disease and familial periodic paralysis there is muscular weakness, while in hypocalcemia, excessive chloride loss and hyperventilation alkalosis there are