Objective:To develop a RP-HPLC method for determination of Morin-3-O-α-L-lyxopyranoside and Morin-3-O-α-L-arabopyranoside in Psidium guajava L.. Methods: A Diamonsil C18 column (250 mm×4.6 mm

5 μm) was used

methanol-0.1% phosphoric acid solution (35∶65)as the mobile phase

flow rate at 1.0 mL·min-1

and the detection wavelength was 355 nm. Results: The of calibration curve Morin-3-O-α-L-lyxopyranoside was linear between 0.061 32 ～ 0.143 08 μg(r=0.999 9 )

The calibration curves of Morin-3-O-α-L-arabopyranoside was linear between 0.058 44 ～ 0.136 36 μg(r=1)

The average recoveries were 98.6% and 100.7%

The relative standard deviations were 1.0% and 1.7%. Conclusion: The method could be used for determination of Morin-3-O-α-L-lyxopyranoside and Morin-3-O-α-L-arabopyranoside from Psidium guajava L..