Purpose: To evaluate and to compare the possible toxic effects of oxcarbazepine (OXC) and valproic acid (VPA) on retinal ganglion cells (RGCs) in rat. Methods: Forty female Wistar rats (21-24 days old and weighted between 44.6 and 57.3 g) were divided equally into 4 experimental groups which were applied tap water (group 1), 300 mg/(kg day) VPA (group 2), 100 mg/(kg day) OXC (group 3), and both VPA and OXC (group 4) via gavage for 90 days. Enucleation was performed for histopathologic analysis. RGCs were counted under the light microscopic examination. Results: RGC numbers in OXC and combined OXC-VPA groups were found to be lower than those of control group. On the other hand RGC number was comparable with those of control group in VPA group. Conclusion: OXC seems to be toxic to RGCs at 100 mg/kg dose when it is been given as a monotherapy or combined with VPA. Single VPA treatment has no effect on RGC number. © 2009 British Epilepsy Association.