The health benefits associated with tea consumption have resulted in the wide inclusion of green tea extracts in botanical dietary supplements, which are widely consumed as adjuvants for complementary and alternative medicines. Tea contains polyphenols such as catechins or flavan-3-ols including (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG), as well as the alkaloid, caffeine. The contents of catechins and caffeine in green tea are considered as a standard of quality evaluation of green tea. Therefor, the purpose of this study was to investigate the most suitable HPLC condition for simultaneous determination of catechins and caffeine in green tea extracts. The efficient HPLC analytical condition of catechins and caffeine contained green tea extracts was developed. The gradient elution employed a $250;mm;{ imes};4.6;mm$ i.d. YMC-pak ODS-AM 303 column. The gradient system was used two mobile phases. A gradient elution was performed with mobile phase A, consisting of 0.1% aqueous phosphoric acid, and mobile phase B, comprising 100% MeOH, and delivered at a flow rate of 1 mL/min as follows: $0{sim}25;min$, 80% A; $26{sim}50;min$, $80{sim}70%$ A; 51 min, 80% A. $51{sim}55;min$, 80% A. The UV detection wavelength was set at 280 nm. The limit of detection (LOD) for catechins and caffeine standards were under 50 ng/mL.