This study examined the antioxidant activities of water extract of Eruca sativa Mill., which is a plant used as both herbal medicine and food in Turkey. The antioxidant activity of water extract of Eruca sativa Mill. was evaluated using different antioxidant test such as reductive potential, free radical scavenging, metal chelating activity, hydroxyl radical activities. In addition, total phenolic compounds in the extract of Eruca sativa Mill. were determined as pyrocatechol equivalent. Those various activities were compared to standard antioxidants such as, cc-tocopherol, butylated hydroxyanisole and butylated hydroxytoluene. The results obtained in this study indicate that Eruca sativa Mill. is a potential source of natural antioxidant.