Fifty cases of complicated hydatid cyst of the liver on a total of 250 cases of hydatid cyst observed were analyzed. The Authors describe the several complications observed (compression, infection, rupture into biliary tract or into the thorax or into the peritoneal cavity, the diagnostic and therapeutic procedures. Total mortality was about 7.6% (3 cases) 2 patient died for intraperitoneal rupture and one for rupture in the biliary tract. Surgical treatment should be as radical as possible performing total or subtotal pericystectomy, hepatic resection is reserved to selected cases. Drainage by Kehr tube of biliary tract is necessary of rupture of the cyst in the biliary tract, while we limit the indication for a papillostomy to the sphincter duct stenosis.