A simple method for the determination of carbamazepine and its active metabolite carbamazepine- 10, 11 -epoxide by ultra performance liquid chromatography (UPLC) with ultraviolet absorbance detection (TUV) was developed. The method involves a two-step protein precipitation by liquid-liquid extraction. Phenytoin sodium was used as the internal standard. The separation was carried out on Acquity C18 column with acetonitrile: methanol: KH2PO4 buffer (adjusting pH to 4.6 with 85% o-phosphoric acid) (180/180/170, v/v/v) as the mobile phase at a flow rate of 0.4 mL min(-1). Linear detection response was obtained for concentrations ranging from 50 to 5,000 ng mL(-1). The limit of quantification (LOQ) was 50 ng mL(-1). The method was validated successfully for the determination of carbamazepine and its active metabolite carbamazepine- 10, 11 -epoxide, which can be applied through pharmacokinetics and bioequivalence studies.