Simultaneous bilateral spontaneous pneumothorax is an uncommon and serious medical problem frequently related to an underlying lung disease such as parenchymal lung disease, inflammatory events or neoplasms. Recurrent pneumothorax associated with persistent air leakage may pose a therapeutic dilemma in patients with underlying lung diseases. Caroli disease (CD) is a very rare congenital disorder characterised by intrahepatic biliary cystic dilatations and frequently associated with polycystic kidney and hepatic fibrosis. To date, no relation between CD and the bilateral diffuse cystic structure of pulmonary parenchyma has been described. In this paper we present a patient with the diagnosis of CD in whom simultaneous bilateral spontaneous pneumothorax was the initial finding due to severe underlying pulmonary disease. Our patient's demographic and clinical characteristics, laboratory findings and course made us exclude the other aetiologies leading to such diffuse multi-bullous pulmonary involvement. The coincidence of recurrent pneumothorax and severe pulmonary disease has led to a big therapeutic dilemma. Open or minimally invasive surgery could be morbid or even mortal because of the nature of the parenchyma and the operative risk due to CD. Therefore, we suggest a unique conservative management including tube thoracostomy by locating the correct air spaces with the aid of high-resolution computed tomography followed by talc pleurodesis in patients with severe multi-bullous lung disease associated with potential risks due to co-morbidities. Copyright (C) 2006 S. Karger AG, Basel.