A 41-year-old woman presented with a 6-month history of gradually progressive postural instability and dysarthria associated with cerebellar and extrapyramidal signs. No Kayser-Fleischer (K-F) rings were observed on biomicroscopic examination of each cornea. The only evidence of hepatic dysfunction was a modest elevation of alanine-aminotransferase. The diagnosis of Wilson disease (WD) was based on low serum ceruloplasmin, abnormal serum copper and urinary copper excretion, and DNA marker segregation analysis. WD should be considered in the presence of characteristic neurologic and laboratory features, regardless of age at onset, evidence of hepatic dysfunction, or absence of K-F rings.