Polycystic liver disease (PLD) is proven to occur either sporadically or in association with autosomal dominant polycystic kidney disease (ADPKD), whereas the existence of an isolated (i.e., without any kidney cyst) familial form is disputed. We describe a family with definitely isolated PLD transmitted through three generations and exclude the linkage of the disease to the genetic markers of PKD1 and PKD2, the two main loci responsible for ADPKD. These findings strongly support the existence of PLD as a genetic disease distinct from the known forms of ADPKD.