Twenty-four preterm infants with respiratory failure from severe hyaline membrane disease (HMD) received mechanical ventilation at high respiratory frequencies. The average birthweight of the infants was 1244 +/- 301 g, and 7 babies weighed less than 1000 g. The average gestational age was 30 +/- 2 weeks, and 6 infants were born at 28 weeks or less. The method of ventilation included (1) respiratory frequencies of 60--110/min, sometimes with brief manual ventilation at more rapid rates, (2) peak inflation pressures (PIP) of less than 35 cm H2O, (3) inspiratory durations of 0.15--0.25 sec, (4) positive end-expiratory pressure (PEEP) of 4--9 cm H2O, and (5) weaning from mechanical ventilation by reducing tidal volume until peak inflation pressure (PIP) reached 20--25 cm H2O, whereupon respiratory frequency was decreased. PaCO2 was kept at 30--40 torr and PaO2 at 60--80 torr. Of the infants, 22 survived (92%) with few major complications.