This study was designed to evaluate the therapeutic effectiveness and adverse effects of carbamazepine, valproic acid, topiramate, and their combination in Iraqi epileptic patients. Ninety epileptic patients were participated in this study, their age ranged from (1-45) years. Seventy patients were previously diagnosed with epilepsy and received antiepileptic drugs for at least six months before this study (retrospective groups). The remaining patients were newly diagnosed with epilepsy (prospective groups). Twenty healthy subjects were selected to be a normal group for the purpose of comparison. The results showed that 90%, 75%, and 60% of patients in retrospective groups were seizure free after 3 months of treatment with carbamazepine, valproic acid, and topiramate respectively. On the other hand, only 45% of patients on combination therapy were seizure free. Whereas in prospective groups, 80% and 100% of the patients were seizure free after treatment with carbamazepine and valproic acid respectively. Serum levels of carbamazepine and valproic acid within the therapeutic range were found in about half of patients. While the remaining patients had their serum levels either in subtherapeutic or in toxic level. The treatment was associated with a significant elevation in hepatic serum enzyme levels that was usually mild and asymptomatic and less than twice the upper limit of normal in all groups. The adverse effects developed were mild to moderate in nature. In conclusion, carbamazepine was more effective in retrospective groups; while, valproic acid in prospective groups was slightly more effective than carbamazepine in controlling seizures; moreover, mono therapy was more effective than combination therapy. TDM showed a poor correlation between the serum concentration of carbamazepine and valproic acid and their therapeutic and adverse effects.