Intrastriatal transplantation of embryonic dopaminergic tissue is a new, experimental approach for the treatment of Parkinson's disease (PD). Clinical trials have shown longterm graft survival and therapeutically valuable improvements with decreased L-dopa dose and time spent in the "off"-phase, and reduced rigidity and hypokinesia. We have measured health-related quality of life (HRQoL) using the Nottingham Health Profile (NHP) in five patients subjected to bilateral transplantation in the caudate and putamen to explore the influence of intrastriatal grafts on HRQoL and the value of such measures in trials of restorative therapies. The results demonstrate improved HRQoL following transplantation, with individual patients showing striking improvements within different dimensions of the NHP as well as the NHP distress index (NHPD). The most pronounced improvements after grafting were observed for physical mobility along with emotional reactions and energy. These results indicate that intrastriatal transplantation of embryonic dopaminergic tissue can give rise to improvements within most areas of HRQoL, and that HRQoL measurements provide important information additional to that obtained by traditional, symptom-oriented assessment protocols. However, the optimal approach to HRQoL measurement in PD remains to be determined.