Background: DBS is a surgical method of choice for various movement disorders, especially for Parkihson's disease (PD). Many publications showing improvement in motor symptoms and quality of life have been presented while there is little comprehensive research evaluation of the impact of DBS on mental state and psychiatric side-effects. Object: The purpose of this study was to assess the impact of DBS on mood, drive, anhedonia and psychotic symptoms in the group of PD patients. Methods: 60 patients with PD were treated with STN-DBS. Mental state and psychiatric side effects were assessed with the use of MADRS, HADRS, BDI, BPRS, YMS, SHADS, CGI and PGI rating scales. Evaluation was performed five times in the period from the day before surgery to six months after implantation of the DBS. Results: This study showed an improvement of mood, which has followed within a month after the start of stimulation and manifested in MADRS, HADRS, BDI scores reduction. The trend towards improvement was maintained over the following 6 months. No manic episodes appeared, 2 cases of mild hypomania were observed. Psychotic symptoms occurred in 1 patient. Anhedonia reduction observed during the first 30 days after initiating the stimulation persisted in the assessment six months after implantation of the DBS. Conclusions: The survey results confirm the effect of stimulation on mood, drive, ability to feel pleasure. Psychiatric side effects such as phase change were rare and mild, while psychotic symptoms that occurred in one patient ware manageable through medication. Further intensive research in this topic are required. (C) 2017 Elsevier B.V. All rights reserved.