H untington's disease (HD) is a progressive disorder with no known cure. We report two-year postoperative positron emission tomography (PET) data from 7 HD patients who underwent intrastriatal fetal transplantation. Patients showed widespread reductions in glucose uptake with no significant change over 2 years. Dopamine receptor binding was significantly reduced in HD striatum. D1 binding did not change significantly following transplantation, but there was a significant loss of D2 binding. These findings may reflect loss of graft viability and/or disease progression. There was no significant relationship between changes in PET and clinical function. In summary, there was no benefit from transplantation. Ann Neurol 2005;58:331–337