Hepatoblastoma (HB) is the most common primary malignant neoplasm of the liver in children below the age of 5 years. This is a heterogeneous tumor composed of various epithelial and mesenchymal elements. Based on these various elements HBs are classified into 4 epithelial subtypes and 2 mixed subtypes. Although a rare tumor, the incidence has increased in the last decades, a period of time that corresponds to increased survival of premature infants of low birth weight. Most tumors are sporadic. Patients with congenital syndromes such as familial adenomatous polyposis and Beckwith–Wiedemann syndrome have a significantly by increased risk for the development of HBs. These disorders have provided an insight into the molecular pathophysiology of HBs, pointing to an up-regulated Wnt signaling pathway by defects in beta-catenin degradation. New understanding of the underlying molecular mechanisms may provide new therapeutic tools in the treatment of these tumors. Recent improvements in chemotherapy have increased the number of resectable tumors, therefore improving survival.