A case of secondary hydatosis, initially misdiagnosed as pulmonary metastases, is presented. The dissemination of hydatid cysts within the lungs in this case was the consequence of direct rupture of a hepatic hydatid into the inferior vena cava. A brief overview of the pathophysiology of hydatid disease, including a discussion of the types of hydatid rupture (contained, communicating and direct), is presented.