Antioxidants from fruits, vegetables and beverages play an important role in human health, for example preventing cancer and cardiovascular diseases, and lowering the incidence of different diseases. In this paper the main classes of antioxidants are presented: vitamins ( vitamin C and vitamin E); carotenoids; polyphenols (flavonoids, flavonols, flavones, flavanones, anthocyanins, isoflavones); phenolic acids; tannins; stilbenes; and lignans. Recently, many analytical methodologies involving diverse instrumental techniques have been developed for the extraction, separation, identification and quantification of these compounds. The main methods of antioxidant extraction are: extraction with solvents, extraction with supercritical fluids, microware-assisted extraction, subcritical water extraction, ultrasonics, pulsed electric fields, high hydrostatic pressure, high voltage electrical discharges and enzyme-assisted extraction. Antioxidants have been quantified by different researchers using one or more of these methods: in vivo, in vitro, electrochemical, chemiluminescent, electron spin resonance, chromatography, capillary electrophoresis, nuclear magnetic resonance, near infrared spectroscopy and mass spectrometry methods.