OBJECTIVES: To assess the impact of DBS of the STN on HRQOL and on Health care resource use in French advanced parkinsonian patients and to estimate the cost of the procedure. METHODS: SPARK is an observational prospective multicentre study using a before-after methodology carried out between November 98 and March 2002 in a cohort of 88 patients with severe Parkinson's disease (PD). Quality of life was assessed before surgery and at 12-month follow-up using a specific instrument, the PDQL 37 (Parkinson's Disease Quality of Life) that has a 3-month recall period. The resource use data were monthly collected from individual questionnaires. Two periods of observation were considered: the first 6 months prior surgery and from the 6th to the 12th month after surgery. The cost of the procedure (surgery, material and checkups over 1 year) was assessed from data collected in the 4 centres. The economic analysis was performed from a Health Insurance perspective. RESULTS: About 66% of patients were men. The mean age of patients was 57.3±7.7 years with a mean duration of PD of 13.9±5.0 years. At 12-month follow-up after surgery, the quality of life was significantly improved (+28%, p <0.0001). All the PDQL subscores were concerned by this improvement, especially the social dimension (+43.5%, p <0.0001). The average 6-monthly cost decreased from € 10,087±4,887 prior surgery to €1,673±2,111 after surgery (€-8,415±4,438, p <0.0001). Taking into account costs related to adjustments of the parameters of the stimulator, the difference was reduced but remained significant: €-7,275±5,128 (p <0.0001). The most important savings came from a dramatically decrease in medication use. CONCLUSIONS: Our findings showed a significant impact of DBS on HRQOL and on medical resource use in patients with PD.