To study transient ventilatory changes in [human] infants with the near-miss sudden infant death syndrome (SIDS), the distribution, frequency, and mean duration of all respiratory pauses (defined as expiratory time (Te) greater than 2 s) were examined in 12 infants with near-miss SIDS and 10 age-matched normal infants during REM [rapid-eye-movement] and quiet sleep at 1, 2, 3 and 4 mo. of age. Using the barometric method, ventilation and respiratory timing were monitored while these infants breathed ambient gas concentrations or 2% CO2. Infants with near-miss SIDS did not have more frequent or prolonged respiratory pauses than did normal infants at any age in REM or quiet sleep breathing ambient gas. With 2% CO2, respiratory pauses decreased in number or were eliminated and their mean duration was shorter in both groups. If these infants have hypoxemia during sleep, hypoxemia is not secondary to prolonged and more frequent respiratory pauses.