Background: carbamazepine and Na-vaplroate acid are two drugs that" widely used in treatment of epileptic patients. In some previous studies have been shown that these drugs change level of the serum lipids and liver function tests (3,4,5). For examples in one study have been shown that carbamazepine increases serum lipids but valproic acid doesn't (3). In the same study these drugs have no effect on SGOT & SGPT but increases GGT (3).It is necessary to mention that this study has not previously performed in Iran. Investigation about the effect of two antiepileptic drugs; carbamazepine and valproic acid on serum lipids and liver function tests in epileptic patients under the age of thirty, treatment 6 months and comparison with each other.Material and Method: This study was a descriptive study and its cases were the patients of Alzahra Emergency room and AI-Zahra and Khorshid clinics. There are two groups (A&B) of epileptic patients in this study. Each group consists 40 patients. Patients of group A have been treated with carbamazepine at least for 6 months and patients of group B have been treated with valproic acid at least for 6 months. Patients of both groups are not more than 30 years old. In this study tested serum lipids (TG, Te. LDL HDL) and liver function tests (SGOT, SGPT, PT) and then deterll1ined the mean of each parameter in each group to compare them with each other. Data of this study were analyzed by Mann- Whitney test.Results: In this study the mean of TG, HDL, SGOT, SGPT and PT are not significantly different between group A and group B (pv>0.05).Conclusion: But the mean of TC and LDL are significantly different between the both groups (pv<0.05). In other words the means of TC and LDL are significantly greater in the patients of group B treated with valproic acid.