Objectives: The aim of this study was to review the prevalence of cognitive impairment in patients with Parkinson′s disease (PD) in Split-Dalmatia County, to investigate effects of other variables on the cognitive status and its impact on the patients’ quality of life. Subjects and methods: This descriptive cross-sectional study was conducted at the Department of Neurology. The study included 39 patients suffering from PD. The data was collected in the period from October 2017, ending in May 2018. We started the examination with an insight into the medical documentation where the demographic and medical information about our subjects were collected. Subjects were than examined and asked to fill out PD specific questionnaires: MoCA, Hoeh and Yahr scale, UPDRS, PDQ-39, daily activity scales by Schwab and England. In order to analyze the given variables we used Mann-Whitney U test, Shapiro-Wilk test, and the Pearson coefficient of correlation. Results: Most of the patients who participated in the research scored less than 26 points on the MoCA questionnaire, which indicates a mild cognitive impairment and/or dementia. There hasn’t been found a statistically significant difference among men and women in the results of the MoCA questionnaire. Age has proven to be a risk factor for the development of cognitive dysfunctions. The duration of the disease did not affect the cognition test results. The MoCA questionnaire domains of visuospatial/executive abilities, attention, language, abstract thinking, and delayed recall showed statistically significant difference in outcome between patients with cognitive impairment (MoCA<26) and with normal cognition. A connection was established between results of the MoCA questionnaire and the stage of disease by Hoehn and Yahr. Patients in the severe stage of disease achieved the worst results. A correlation was also established between the MoCA questionnaire results and the UPDRS scale that tracks the development of the disease symptoms. As a result of the progression of motor symptoms of the disease and a consequently higher average of the use of levodopa, the cognitive ability of patients with PD is in decline. A correlation was also found between the quality of life and cognitive assessment tests. Individuals with a better quality of life performed better results on cognitive assessment tests. Conclusions: Cognitive dysfunction in the range of mild cognitive impairment to dementia is common symptom of PD patients. A common symptoms in PD patients are cognitive deficit, specifically in the domains of the visuospatial/executive abilities, attention, language, abstract thinking and delayed recall. The age of patient during the diagnosis of the disease and at the time of the survey has a negative impact on cognitive abilities, whereas sex and length of the disease do not affect cognitive abilities. Patients in the severe stage of disease achieved the worst results on the MoCA questionnaire. Cognitive functions affect the patient’s quality of life to a great extent.