Sixty newborn infants who had been mechanically ventilated through 3.0- or 3.5-mm endotracheal tubes were studied to examine the necessity of a preextubation trial of continuous positive airway pressure (CPAP). Thirty randomly assigned study infants were directly extubated from intermittent mandatory ventilation rates of six per minute; 30 randomly assigned control infants were extubated after a six-hour trial of continuous positive airway pressure of 3 cm H2O. Changes in respiratory rate, in PCO2, and in PO2/FIO2 were similar. All 30 study infants tolerated direct extubation without significant apnea or respiratory acidosis. Two study and eight control infants developed apnea during six hours after intermittent mandatory ventilation was discontinued (chi 2 = 4.3, P less than .05). Five control and no study infants had apneic episodes greater than or equal to 0.5 per hour (chi 2 = 5.5, P less than .02). The results of this study suggest that newborn infants may tolerate direct extubation from low intermittent mandatory ventilation rates without a preextubation trial of CPAP. A preextubation trial of CPAP appears to be unnecessary and may cause more frequent apnea in newborn infants if used for more than several hours.