OBJECTIVES: Show whether there is a statistically significant difference in length of the P300 wave latency of targeted and untargeted stimulus and statistically significant difference in the P300 wave amplitude of targeted and untargeted stimulus between group of patients with Parkinson's disease compared to reference value for healthy population. PATIENTS AND METHODES: The study was designed as a cross-sectional study. Conducted at the Reference Centre for evoked potentials Ministry of Health of the Republic of Croatia, Department of Neurology, University Hospital Split. Data were collected in the period from May 1st 2015. until January 1st 2016. The study included 21 patient suffering from Parkinson's disease. After reviewing the medical records and analyzes the inclusion and exclusion criteria, patients were subjected to the same procedure examining auditory cognitive potentials (P300 wave) and the results were analyzed and compared to reference value for healthy population. RESULTS: We demonstrate a statistically significant difference in the median length of the P300 wave latency of target stimulus between group of patients with Parkinson's disease compared to reference value for healthy population. The median length of the P300 wave latency of target stimulus in patients with Parkinson's disease was 314.76 ms (299-326) until as the reference value for healthy population was taken value of 300± 10 ms. We have olso shown that there is a statistically significant difference of the median length of the P300 wave latency of untargeted stimulus. The median length of the P300 wave latency of untargeted stimulus in patients with Parkinson's disease was 345 ms (319-353) and reference value for healthy population was 300± 10 ms just like one in the P300 wave latency of target stimulus. By analyzing the P300 wave amplitude of target stimulus in the group of patients suffering from Parkinson's diseas of 21 patient, 18 had abnormal findings. Regarding the P300 wave amplitude of untargeted stimulus, of 21 patient, 20 of them had abnormal findings. CONCLUSIONS: Patients suffering from Parkinson's disease have prolonged the P300 wave latency both of targeted and untargeted stimulus compared to reference value for healthy population. Except for prolonged latency, they have reduced the P300 wave amplitude of targeted and untargeted stimulus compared to reference value for healthy population.