Ataxia-telangiectasia (A-T) is a rare autosomal recessive multisystem disorder with a short life expectancy. During adolescence pulmonary complications are common in A-T patients, and respiratory failure is the most important cause of death. Therefore mechanical ventilation is often considered in these patients. In this study we retrospectively evaluated the clinical characteristics and ICU course of three consecutive adolescent A-T patients who were mechanically ventilated for respiratory failure. None of these patients had a history of respiratory infection. In all patients volume-pressure ratios indicated severe restrictive lung dysfunction. This was supported by data on pre-admission lung function testing. All three patients died of hypercapnic respiratory failure during ICU admission. The study shows that severe restrictive lung function is a common finding in adolescent A-T patients which may seriously complicate ventilatory treatment. Preadmission lung function testing is essential for the optimal medical management of these patients. Copyright © 2009, Nederlandse Vereniging voor Intensive Care. All Rights Reserved.