Solitary biliary cysts and polycystic liver disease are among the most frequent cystic lesions of the liver. Solitary biliary cysts have a prevalence of 1 to 2 percent; they are almost always asymptomatic and do not require treatment. Ultrasonography shows a regular, round or oval, entirely liquid and trans-sonic image sufficient to make the diagnosis. Complications are exceptional. Polycystic liver disease is associated with polycystic kidney disease in 50 percent of the cases, and the prognosis depends on the degree of renal failure. In polycystic disease of the liver and kidney the hepatic cysts develop before the renal cysts. Complications (e.g. cyst infection) are rare and principally observed in patients with terminal renal failure. In patients with complicated polycystic liver disease various treatments, such as needle aspiration, alcohol sclerotherapy or surgery, must be considered.