Objective: The purpose of this study was to examine pulmonary function tests in children at various time points in their recovery from empyema. Design: Cross-sectional study. Setting: Academic Children's Hospital. Patients: Pediatric patients with a diagnosis of empyema between 1992-2000. Results: A total of 45 pulmonary function tests were carried out in 36 study participants. Within 3 months of hospital discharge, 91% of pulmonary function tests demonstrated a restrictive pattern with a mean forced vital capacity (FVC) of 69.2 ± 4% and a mean total lung capacity (TLC) of 74.9 ± 4% of predicted. The incidence of restriction in pulmonary function significantly decreased over time and for patients tested >1 year from hospital discharge the mean FVC was 87.1 ± 2% and the mean TLC 95.0 ± 2% of predicted. However, 19% of the patients tested >1 year from discharge demonstrated a mild restrictive pattern and 16% demonstrated mild obstructive changes. Patients with abnormal lung function >1 year from hospital discharge did not demonstrate any signs or symptoms of respiratory insufficiency. Conclusion: There is a high incidence of restrictive patterns in lung function for children tested within 3 months from hospital discharge for empyema. The incidence of restrictive patterns decreased significantly over time and most patients tested >1 year from hospital discharge demonstrated normal lung function.