We investigated the role of chest physiotherapy (CPT) in preventing post-extubation atelectasis (PEA) in infants. Sixty-three infants who were admitted to the neonatal intensive care unit and intubated for more than 24 hours and who showed no evidence of atelectasis by chest x-ray prior to extubation were enrolled in the study. Infants were randomly assigned to 2-hourly CPT, 4-hourly CPT, or a no CPT group. Chest physiotherapy began immediately after extubation and consisted of postural drainage, bilateral chest vibration, and suctioning. A second chest x-ray was obtained on all infants 24 hours following extubation. The three groups were comparable in birth weight, gestational age, and duration of intubation. In the 24-hour period following extubation, the incidence of PEA was not statistically significant in the three groups (P = 0.33). Two infants in the 2-hourly CPT group were placed on nasal continuous positive airway pressure; two in each of the 2-hourly and the no CPT groups required re-intubation and intermittent positive pressure ventilation to treat symptomatic atelectasis. We conclude that post extubation chest physiotherapy as used in this study did not prevent atelectasis in extubated infants.