Sulforaphane (SFN) is a natural, biologically active compound extracted from cruciferous vegetables such asbroccoli and cabbage with anti-inflammatory and anti-cancer properties. The present study was carried to assesscytoprotective potential in alleviating oxidative stress, to influence the initiation and subsequent carcinogenesiscaused by benzo(a)pyrene [B(a)P] administration in the pre- and post-initiation phases of carcinogenesis in Swissalbino mice. Sulforaphane, supplemented orally at a dose of 9μmoles /mouse/day was found to greatly lessenthe damaging effects of B(a)P in mice by increasing the availability of reducing equivalents to fulfil the futileGSH redox cycle and replenish GSH biosynthesis, stabilizing the thiol status. Activity of superoxide dismutaseand catalase in native gel prove their differential activities in cancer induced and treated animals. SFN was alsofound to prevent formation of leaky membranes by boosting the antioxidant status leading to maintenance ofATPase activity in B(a)P treated animals. Histopathological analysis confirmed reduction of carcinogen-associatedmorphological changes in the lung tissue. The results suggest that SFN has potential as a chemopreventivephytochemical against B(a)P induced lung damage in the processes of carcinogenesis.