OBJECTIVE: The main purpose of this study was to examine impairment in cognitive functions in patients with epilepsy using the screening method. The specific goal of this research was to determine whether there is correlation between the impairment in cognitive functions and the duration of the disease as well as with the antiepileptic treatment itself, and to determine which cognitive functions are more exposed to the effect of AED. STUDY DESIGN: The research is organized as a prospective cross-sectional study. PARTICIPANTS AND METHODS: The research included thirty patients who are using antiepileptic therapy and are treated at the Department for epilepsy, the Clinic of Neurology at Clinical Hospital Center Osijek. The instruments used as research tools to collect data on demographic characteristics of patients and data on clinical variations related to epilepsy included: anonymous questionnaire structured for the purposes of this research and Montreal Cognitive Assessment test (MoCA). RESULTS: Out of thirty patients included in this study, 16 (53%) were male and 14 (47%) female. 22 (73%) patients have changed their antiepileptic therapy since they started taking it. Their therapy was changed 3 times on average, ranging from 1 to 10 times. Patients are using 3 different types of medication on average, ranging from 2 to 6 different medications. The analysis of MoCA has revealed a negative correlation between the number of drugs patients are taking and total MoCA score (Spearman’s correlation coefficient Rho= -0.561, P = 0.02). These results indicate that the more types of medication patients take, their visual-spatial/executive functions (Rho = -0.602, P = 0.008), attention (Rho = -0.469, P = 0.04), delayed memory (Rho = -0.473, P = 0.04) and total MoCA score are worse. CONCLUSION: Epilepsy and antiepileptic medications affect cognitive functions of patients with epilepsy. There is a negative correlation between the number of antiepileptic medications and the total MoCA score. Patients who take fewer medications in their therapy have significantly higher score in cognitive domains including concentration, delayed memory and visual-spatial/executive functions than patients taking polytherapy.