Respiratory failure seen in very low birth weight infants (VLBW) usually results from respiratory distress syndrome (RDS). The use of steroids and surfactant has had a major impact on RDS severity, but has not eliminated the problem. Furthermore, neither steroids nor surfactant have eliminated chronic lung disease (CLD). This suggests the need to evaluate other therapeutic interventions, which will reduce the incidence and/or severity of neonatal RDS and CLD. Studies have shown that high frequency oscillatory ventilation (HFOV), improves gas exchange in injured lungs, and reduces pulmonary injury by avoiding the large changes in intrapulmonary pressure and volume necessitated by tidal ventilation (SIMV). The purpose of this study is to see if HFOV is better than SIMV in VLBW infants requiring ventilary support. Progress to Date: 17 patients have been enrolled, 9 of which have completed the study and did well, 6 remain on study and are doing well, 1 patient withdrew (parental request), and 1 expired due to prematurity.