Abstract A 39-year-old Japanese woman was admitted to our hospital for severe weakness owing to potassium deficiency caused by type 1 renal tubular acidosis (RTA1). Sicca complex, serological tests, and lip biopsy revealed that she had Sjogren's syndrome (SS). Acidosis was corrected by alkali supplement treatment. She also had an impaired renal function with proteinuria, and high absorbance on Ga scintigram was recognized in both kidneys. She was taking warfarin potassium after aortic valve substitution due to aortic regurgitation, therefore renal biopsy was not performed. Prednisone (20mg/day) was administered for renal inflammation. One month later, she suffered severe chest wall pains with some local tender points over the costae of both sides, which was presumed to be due to pseudofractures based on osteomalacia. Hypokalemic paralysis and osteomalacia should be taken into consideration in the diagnosis of SS with RTA1.