A 3-year-old girl presented with hemolytic anemia, hepatosplenomegaly, ascites, and evidence of decompensated chronic liver disease. Genotypic DNA analysis revealed that the patient was homozygous for a splice site mutation now designated IVS4-1:G>C, expected to destroy completely the functional gene product of ATP7B, the gene responsible for Wilson's disease. We suggest that this severe mutation caused very early liver disease. Wilson's disease should be considered in the differential diagnosis of established liver disease in the preschool-aged child.