BACKGROUND: We evaluated whether eye movements could reflect the efficacy of antiepileptic drugs in patients with epilepsy. METHODS: Thirty patients with epilepsy of unknown cause as well as age- and sex-matched normal controls were enrolled in this study. We divided the patients into drug-controlled epilepsy (n = 22) and drug-resistant epilepsy (n = 8) groups according to their seizure controls. We analyzed the differences in the parameters of the eye movements in these two groups compared with normal controls using video-based electro-oculography. In addition, we investigated the differences in the cerebellar volumes of these two groups using whole-brain T1-weighted images. RESULTS: The latency and accuracy of saccade in patients with epilepsy were significantly different from normal controls, but they were not different between patients with drug-controlled epilepsy and drug-resistant epilepsy. However, the gain of pursuit was significantly decreased in patients with drug-resistant epilepsy compared with normal controls (p = 0.0010), whereas it was not different between patients with drug-controlled epilepsy and normal controls (p = 0.9646). In addition, the patients with drug-resistant epilepsy had lower cerebellar volumes than normal controls (p = 0.0052), whereas the cerebellar volumes in patients with drug-controlled epilepsy were not different from normal controls (p = 0.5050). CONCLUSIONS: We demonstrated that pursuit eye movements could reflect the efficacy of antiepileptic drugs in patients with epilepsy, a finding that may be related to cerebellar dysfunction.