The volatile flavor components of the fruit pulp and peel of orange (Citrus sinensis) and grapefruit (Citrus paradisi) were extracted by simultaneous distillation-extraction (SDE) using a solvent mixture of n-pentane and diethyl ether (1:1, v/v) and analyzed by gas chromatography-mass spectrometry (GC-MS). The total volatile flavor contents in the pulp and peel of orange were 120.55 and 4,510.81 mg/kg, respectively, while those in the pulp and peel of grapefruit were 195.60 and 4,223.68 mg/kg, respectively. The monoterpene limonene was identified as the major voltile flavor compound in both orange and grapefruit, exhibiting contents of 65.32 and 3,008.10 mg/kg in the pulp and peel of orange, respectively, and 105.00 and 1,870.24 mg/kg in the pulp and peel of grapefruit, respectively. Limonene, sabinene, ${\alpha}$-pinene, ${\beta}$-myrcene, linalool, (Z)-limonene oxide, and (E)-limonene oxide were the main volatile flavor components of both orange and grapefruit. The distinctive component of orange was valencene, while grapefruit contained (E)-caryophyllene and nootkatone. $\delta$-3-Carene, ${\alpha}$-terpinolene, borneol, citronellyl acetate, piperitone, and ${\beta}$-copaene were detected in orange but not in grapefruit. Conversely, grapefruit contained ${\beta}$-pinene, ${\alpha}$-terpinyl acetate, bicyclogermacrene, nootkatol, ${\beta}$-cubebene, and sesquisabinene, while orange did not. Phenylacetaldehyde, camphor, limona ketone and (Z)-caryophyllene were identified in the pulp of both fruits, while ${\alpha}$-thujene, citronellal, citronellol, ${\alpha}$-sinensal, ${\gamma}$-muurolene and germacrene D were detected in the peel of both fresh fruit samples.