In a 29-day-old premature infant with respiratory syncytial virus (RSV) pneumonia, we have shown an additive effect of high-frequency oscillatory ventilation (HFOV) and continuous inhalation of prostacyclin (iPGI(2)) with improvement of ventilation and oxygenation. The addition of continuous inhaled iPGI(2) to HFOV was beneficial in the treatment of hypoxemic respiratory failure owing to RSV-associated pneumonia. The improvement in alveolar recruitment by increasing lung expansion by HFOV along with less ventilation-perfusion mismatch by iPGI(2) appears to be responsible for the synergistic effect and favorable clinical outcome. We conclude that the combined therapy of HFOV and continuous inhaled iPGI(2) may be considered in RSV-associated hypoxemic respiratory failure in pediatric patients.