INTRODUCTION:Since extended-release formulations of CBZ have been developed to decrease daily fluctuations in serum CBZ concentrations and improve dosing convenience, several large clinical trials have recently been conducted to assess the efficacy and tolerability of this form of CBZ in bipolar disorder. In the present assessment, extendedrelease carbamazepine has been compared with lithium, in a head-to-head evaluation, to assess its efficacy and safety in a group of non-Western patient population with diagnosis of acute mania. METHOD: Fifty male inpatients with diagnosis of bipolar I disorder, according to Diagnostic and statistical manual of mental disorders, 5th edition (DSM-5), entered into a 3-week study, for random assignment to extended-release carbamazepine or lithium carbonate. The assessment had been accomplished as a double-blind design, while the patients, staff, prescribers, and assessor were unaware of the prescribed drugs that were packed into identical capsules. Primary outcome measure in the present assessment was Manic State Rating Scale (MSRS), which had been scored at baseline and weekly intervals up to the third week. Also, insight and overall illness severity and improvement had been rated by the Schedule for Assessment of Insight (SAI), Clinical Global Impressions-Global Improvement Scale (CGI-I), and Clinical Global Impressions-Severity Scale (CGI-S), respectively. Treatment effectiveness had been analysed by t-test and repeated measures analysis of variance (ANOVA). Statistical significance had been defined as p-value ≤.05. RESULTS: While mean total score of MSRS improved significantly by both lithium and extended-release carbamazepine at the end of the third week, between-group analysis displayed significant advantage of lithium, regarding both frequency and intensity, at the end of trial. Mean total score of SAI showed significant improvement by both of them. However, again, the CGI-I demonstrated significant improvement by extended-release carbamazepine and lithium, CGI-S revealed significant progress only by lithium. Moreover, the effect size (ES) analysis showed large improvement of MSRS with lithium and medium improvement by extended-release carbamazepine. Post hoc power analysis showed an intermediate power of 0.42 on behalf of the present assessment. CONCLUSION: Although both extended-release carbamazepine and lithium were helpful for improvement of manic symptoms, treatment with lithium seems to be more advantageous. ARTICLE HISTORY