Therapeutic drug monitoring (TDM) plays a major role in planning andoptimizing the treatment of a patient, as in the treatment of epilepsy. The monitoring of antiepileptic drugs (AEDs) in the management of epilepsy is crucial because of their complex pharmaco kinetic properties, narrow ther apeuticindex, and wide fluctuations. In this study, weaimed to investi gate the 5-year TDM results of AED, which is one of the mostapplied group stoour laboratory, in terms of age, genderand plasma concentrations (bytherapeutic limit). Weal so aimedto guide clinicians whodi agnose and treat epilepsy patients. This study was conducted toretros pectively analyzethe TDM results of patients in Eskişehir Osmangazi University Hospital between 2013-2018. The AED levels were classified as below, within, and above the referen cerange. The monitored drugs were valproicacid, carbamazepine, phenytoin, phenobarbital, and levetiracetam. The percent of all drug level result sanalyzed for valproicacid, carbamazepine, levetirace tamand pheno barbital was with in the referen cerange. Pheny toins howed wide fluctuation anditssub ther apeutic level was notably high. Inpractice, TDM was foundt o be helpful in the of adjust mentdrug dosage with regard to theres ponse of individual patients.