This study determines some phenolic compounds in four different vegetables (carrots, celery, lettuce and red cabbage) grown in Kerman, Iran. The phenolic compounds (Ascorbate, Ferulic acid, Naringin) were analyzed using reverse phase high performance liquid chromatography (RPUPLC). The results of the study showed that the level of these compounds ranged between 90 and 1080mg / kg. A high and significant correlation was determined between antioxidant activity and total phenolic content of vegetables (r2 = 0.9461 and P < 0.06). However, flavonoid content was not significantly correlated to antioxidant activity in vegetables. It was also observed that total phenolic content is the major contributor to the antioxidant activity of vegetables. The method could be successfully used for quantification of natural vegetables’ antioxidant content. It was also observed that the antioxidant contents of vegetables deeply depend on species, cultivar and horticultural practice and could be considered as an active parameter for authenticity determination.