The quantification of fragrance and flavor substances is focused on highly sensitive instrumental methods and comparison of the resulting signal of sample compounds with those of the reference standards. Tests such as content of chemical compounds and trace impurities are usually conducted by techniques such as Gas chromatography (GC), high-pressure liquid chromatography (HPLC), capillary electrophoresis (CE), and Nuclear magnetic resonance (NMR). On the other hand, complex mixtures of food matrices require the use of hyphenated techniques such as GC-MS, GC-FTIR, HPLC-MS, CE-MS, HPLC-NMR, and two-dimensional gas chromatography (GC-GC). These are valuable tools for the complete separation of compounds, their identification, and quantification. Likewise, Gas chromatography–olfactometry (GC–O) has become a standard method for the detection and determination of sensory important constituents in complex mixtures. Most hyphenated instrumental techniques can separate and quantify flavor and fragrance compounds such as non-terpenoid hydrocarbons, terpenoids, norterpenoids, phenylpropanoids, esters, lactones, phthalides, isothiocyanates, nitrogen-and-sulphur-containing essential oil constituents. This chapter provides a comprehensive review of hyphenated instrumental techniques for the analysis of flavors and fragrances. A comparison of the two most representative methods for the analysis of an essential oil used in flavors and fragrance products are also discussed.