A total of 4 of 153 low birth weight infants at our hospital were found to have pseudo-Bartter syndrome in 2005 and 2006. The neonates (two of whom were twins; light for gestational age 2, appropriate for gestational age 1 and small for gestational age 1) showed symptoms of apnea and/or poor feeding or patent ductus arteriosus, which disappeared by day 4. Hypokalemia, hypochloremia and metabolic alkalosis normalized by day 8. The mothers had repeatedly rushed to the restroom after eating while in hospital, and were lighter at delivery than before pregnancy; however, vomiting was not observed. The mothers had several stress factors related to pregnancy, and all recovered from the eating disorder after delivery. Urinary Cl/creatinine (mequiv. mg(-1)) and serum Mg in the infants were <0.1 and 1.6 to 2.3 mg per 100 ml, respectively. Eating disorder during pregnancy may have caused Bartter-like syndrome and weight loss, and led to the same syndrome and intrauterine growth retardation in the offspring. Therefore, a hidden maternal eating disorder may underlie neonatal pseudo-Bartter syndrome.