Since its initial description in 1967,1 Kawasaki disease has been further defined and the clinical syndrome continues to expand.2,3 As part of a retrospective review of our patients with Kawasaki disease, we have noted a high frequency of hyponatremia (serum sodium <135 mEq/liter) in patients whose serum sodium was measured on admission to hospital (6/11). Serum sodium values in the six patients were 126 mEq/liter in one, 128 mEq/liter in one, 130 mEq/liter in two, 133 mEq/liter in one, and 134 mEq/liter in one.