This research was undertaken to determine the phenolic composition and antioxidant capacity of juices and wines obtained from Robinson, Fremont and Satsuma mandarins. High-performance liquid chromatography coupled with diode-array detection was used for identifying and quantifying phenolic compounds. The total amount of phenolic compounds ranged from 36.6 to 132.6 mg/L for the mandarin juice, and from 14.1 to 54.5 mg/L for the wines. In the juices and wines, the major hydroxybenzoic acid was vanillic acid; the major hydroxycinnamic acid was ferulic acid; and the major flavanone was hesperidin. The antioxidant activity was measured using the DPPH and ABTS radical scavenging assays, and the antioxidant capacity of mandarin juices was found to be higher than that of wines. Results of this study indicated that these mandarin wines had a composition similar to other beverages, thus demonstrating that these fruits have the potential to be used to produce fermented beverages.