Very low-birth weight infants with patent ductus arteriosus (PDA) accompanied by severe heart failure do not respond to indomethacine therapy. It is essential to stabilize the general condition of these infants until surgical intervention. We tried to regulate the pulmonary blood flow to control congestive heart failure by administering supplemental nitrogen inhalation therapy to six very low-birth-weight infants with PDA. After the inhalation of supplemental nitrogen gas was begun, the arterial oxygen saturation and partial oxygen pressure immediately decreased. Furthermore, the blood pH, systolic pressure, and urine output significantly increased. The infants were well stabilized. Furthermore, there were no complications related to nitrogen gas inhalation. Supplemental nitrogen inhalation therapy is an effective and feasible therapy for severe congestive heart failure in very low-birth-weight infants with PDA.