Research goal: Determine the frequency of monitoring of the new generation antiepileptics concentration during 2018 in the Department of Laboratory Diagnostics of KBC Osijek. To show the number of patients whose concentration was within the therapeutic range. Compare the values of lamotrigine and topiramate with the therapeutic range. Materials and methods: Concentrations of the new generation antiepileptics that are issued by the Department of Laboratory Diagnostics of KBC Osijek in 2018. The antiepileptics concentration was determined by a chromatographic method on LC-MS/MS-8050. Results: During 2018, the new generation antiepileptic drugs concentration was determined 340 times and it was within the therapeutic range in the case of 218 patients. Levertiracetam (155) and lamotrigine (121) are determined as the most frequent antiepileptics determined by the concentration in patients` blood, while lacosamide, oxcarbazepine and rufinamide are shown as the rarest. The highest values within the therapeutic range had the patients who were using zonisamide (91,67%) 64.5% of the concentration of lamotrigine is within the therapeutic range while the median value is 3,8 mg/l. 69 % of the topiramate value is within the therapeutic range while the median value is 4,73 mg/l. Concentrations of lamotrigine and topiramate were not to be considered as normal distribution and there was no significant difference in the concentration of mentioned drugs (Mann Whitney U test, P=0,95). There is no significant statistical correlation between the concentration of lamotrigine and topiramate whilst the results do not deviate significantly from linearity. Conclusion: TDM of new antiepileptic drugs is primarily carried out due to better relationships between blood antiepileptic drug concentration and therapeutic effect. In contrast to topiramate, lamotrigine concentration is more often determined because of the fact that it is to be the most prescribing new antiepileptic. The proportion value of topiramate and lamotrigine is approximately equally within the therapeutic range, while the value of other antiepileptic drugs vary. Statistically, there is no significant deviation from therapeutic range between the concentration of lamotrigine and topiramate.