Aim:The goals of the present study were to assess the health-related quality of life (HRQoL) with the Parkinson’s Disease Questionnaire 39 (PDQ-39) after unilateral subthalamic deep brain stimulation (STN DBS) and to identify correlations between the changes in UPDRS (Unified Parkinson’s Disease Rating Scale) scores and separate PDQ 39 QoL dimensions and PDQ summary index (SI) score at short-term follow-up (FU1) and long-term follow-up (FU2).Material and Methods:We evaluated 33 patients with PD after unilateral STN DBS. All patients were assessed at baseline and at FU1 and at FU2. HRQoL levels were determined by applying PDQ-39 and PD progression was evaluated by parts I-IV of the UPDRS. Results:All dimensions of PDQ-39 as well as PDQ-39 SI score were highly significantly improved at FU1. The same improvements were mostly visible at FU2 except for psychosocial functioning. The PDQ-39 SI score was reduced by 40 % (p<0.01) at FU1 and by 25 % (p<0.01) at FU2. A significant reduction between the UPDRS baseline scores and the UPDRS follow-up scores was noticed for medication off and on conditions under unilateral STN DBS. Interestingly, we did not find strong positive correlations between the improvements of the UPDRS scores and individual PDQ-39 dimensions as well as PDQ-39 SI score.Conclusion:Improvements in PDQ-39 dimensions and PDQ-39 SI score are maintained at FU1 and except for the aspects of psychosocial functioning at FU2. Different correlations between the improvements of separate UPDRS scores on PDQ-39 dimensions require future studies in larger study groups.