Objectives: The aim of this study was to assess the effects of oxcarbazepine (OXC) on cognition and psychosocial difficulties in patients with new-onset partial epilepsy. Methods: Cognitive and psychosocial assessments were performed before and after 6 to 12 months of OXC monotherapy in 52 drug-naive patients (25 women; mean age, 31.1 years; SD, 12.1 years). Cognitive functions were evaluated with well-structured and validated tools. Mood, psychological distress, subjective handicap, and quality of life were also evaluated. Differences between baseline and after-treatment evaluation were compared and adjusted for possible confounders such as age, sex, seizure control, duration of epilepsy, assessment interval, and epileptogenic region. Results: Mean assessment interval was 231.8 (range, 182–348) days, and mean (SD) OXC dose at retest was 693.8 (208.9) mg. The OXC was found to have no significant adverse effect on cognition. Furthermore, OXC monotherapy was not found to affect psychosocial difficulties, including psychological distress and subjective handicap. Conclusions: The results suggest that OXC monotherapy could be used to treat newly diagnosed partial epilepsy without adversely affecting cognitive and psychosocial functions.