A retrospective review was carried out of 11 consecutive patients with the Pierre Robin sequence referred to a tertiary paediatric referral centre over a five year period from 1993 to 1998. Ten patients were diagnosed with significant upper airway obstruction; seven of these presented late at between 24 and 51 days of age. Failure to thrive occurred in six of these seven infants at the time of presentation, and was a strong indicator of the severity of upper airway obstruction. Growth normalised on treatment of the upper airway obstruction with nasopharyngeal tube placement. All children had been reviewed by either an experienced general paediatrician or a neonatologist in the first week of life, suggesting that clinical signs alone are insufficient to alert the physician to the degree of upper airway obstruction or that obstruction developed gradually after discharge home. The use of polysomnography greatly improved the diagnostic accuracy in assessing the severity of upper airway obstruction and monitoring the response to treatment. This report highlights the prevalence of late presentation of upper airway obstruction in the Pierre Robin sequence and emphasises the need for close prospective respiratory monitoring in this condition. Objective measures such as polysomnography should be used, as clinical signs alone may be an inadequate guide to the degree of upper airway obstruction.