The optimal treatment of post-pneumonic thoracic empyema in children is controversial. In this retrospective study, we review our seven-year experience with open surgical drainage in this condition. Between July 1, 1989, and June 30, 1996, 20 children (median age 2.7 years, range 1-8 years) underwent thoracotomy for post-pneumonic empyema in our department. The diagnosis of thoracic empyema was established by the combination of exudate in a pleural tap and the demonstration of multi-loculated pleural effusion by either chest ultrasound or computerized tomography of the chest. The surgical approach was through a posterolateral mini-thoracotomy under general anesthesia, Intrapleural debris, gelatinous, and fibrinous material were evacuated and drains were placed, under vision, at the most dependent pleural locations. The mean length of pre-hospital illness was 5 days (S.D. 3.1 days) and the mean hospital length of stay in a pediatric ward prior to surgery, during which all children received intravenous antibiotics, was 9.4 days (S.D. 7.7 days). A causative pathogen was identified in 8 cases: Streptococcus pneumoniae in 5 cases, Streptococcus group A, and H. influenzae each in one case. Cultures from the pus removed during surgery were sterile for all 19 children who received antibiotics for more than 24 hours prior to surgery. Within 48 hours after surgery, fever dropped to < 37.5 degrees C in 85 % of the cases. The postoperative course was uneventful in all cases and the children were discharged home 9 days (S.D. 2.8 days) after surgery. We conclude that open mini-thoracotomy and removal of the entire empyema sac is a safe and curative procedure for children with thoracic empyema.