Unilateral paralysis is rarely reported to be primary presentation of severe hypokalemia. We describe a 24-year-old woman who presented to the emergency department with sudden onset of right-sided weakness. Neurologic examination revealed diminished muscle strength and tendon reflexes over the right limbs. Computed tomography of the brain showed no organic brain lesion. However, laboratory data showed hypokalemia (K+ 2.0 mmol/L) with metabolic acidosis (HCO3 − 19 mmol/L). She needed a total of 260 mmol K+ to achieve complete recovery of muscle strength at a serum K+ level of 3.2 mmol/L and was proved to have distal renal tubular acidosis. Severe hypokalemia must be kept in mind as a cause of acute unilateral paralysis without organic lesions to avoid unnecessary examination and potentially life-threatening complications.