An HPLC (high-performance liquid chromatography)-PDA (photodiode array) detection method was established for the determination of naringin, hesperidin and neohesperidin in the fruit of Citrus paradisi and C. grandis. The flavonoids were separated in less than 20 min using an YMC RP 18 column with isocratic elution using acetonitrile and water (23 : 77, v/v) at a flow rate of 1 ml/min, and a PDA detector. The levels of naringin, hesperidin and neohesperidin were 1345.92, 950.62, and 2078.82 ${mu}g/g$, respectively, in the peel, and 102.43, 59.13, and 86.68 ${mu}g/g$, respectively, in the flesh of C. paradisi. In C. grandis, the levels of naringin, hesperidin and neohesperidin were 3530.56, 80.00, and 5.26 ${mu}g/g$, respectively, in the peel, and 59.59, 7.43, and 38.41 ${mu}g/g$, respectively, in the flesh. The total content was highest in the peel, reaching 0.44% and 0.36% in C. paradisi and C. grandis, respectively, while the flesh contained only 0.025% and 0.011%, respectively. Therefore, the peels of C. paradisi and C. grandis are necessary for the processing and utilization of flavonoids.