Here, we report the case of a 23-year-old man with type 1 renal tubular acidosis (RTA) associated with osmotic demyelination syndrome (ODS) who developed pontine hemorrhage. Acute progressive tetraparesis had developed during the clinical course of the RTA. Neurological examination revealed bilateral weakness in all 4 limbs associated with severe hypokalemia (K 1.4 mEq/L). He experienced a sudden onset of general convulsions and mutism during the treatment for metabolic acidosis and hypokalemia. The T2-weighted MR image of the brain revealed multiple hyperintense signal lesions in the central pons as well as in the extrapontine sites of the bilateral cortical and subcortical areas in the frontal and parietal lobes. A T2-star (T2*)-weighted MR image showed focal hemorrhagic lesions in the lower pons. On the basis of the diagnosis of ODS, he underwent corticosteroid and thyrotropin-releasing hormone therapy, after which his neurological signs and symptoms have gradually reduced. While analyzing the possible etiology, it has been suggested that osmotic vascular injuries induced by elevated levels of serum potassium and osmolarity give rise to edema and vascular endothelial damage; these conditions, consequently lead to hemorrhagic necrosis. Physicians need to be aware that RTA patients may develop ODS after hypokalemia, and the potassium levels need to be corrected carefully. (Received: November 6, 2007, Accepted: June 11, 2008)