It is essential to differentiate pseudo-Bartter's syndrome from Bartter's syndrome because both are accompanied by hypokalemia and metabolic alkalosis. In this study, we encountered a newborn girl with marked hypokalemia and metabolic alkalosis who was born vaginally at 41 weeks' gestation to a mother with pseudo-Bartter's syndrome and associated eating disorder. Venous blood gas analysis for transient respiratory distress revealed hypokalemia. Because hypokalemia did not improve, the newborn was transferred to our hospital 3 days after birth. Hema tological findings on admission showed serum potassium 2.6 mEq/L, bicarbonate 36.3 mmol/L, and base excess 12.8 mmol/L, with pH 7.56 and metabolic alkalosis. Electrocardiography (ECG) revealed sinus bradycardia as well as ST-segment depression, T-wave flattening, and prominent U-waves in all chest leads. Administration of enteral potassium began on postnatal day 5 but was terminated on postnatal day 7 because of rapid elevation of serum potassium, with consequent reversion of ECG abnormalities to age-appropriate levels. We later learned that the mother's serum potassium level was around 2 mEq/L because of the eating disorder, which frequently caused vomiting. Our findings suggest that this was a case of neonatal pseudo-Bartter's syndrome accompanied by severe electrolyte abnormalities and ECG changes due to maternal pseudo-Bartter's syndrome.