Medicinal plants have served as a source of ‘lead’ compounds for novel drug discovery. Notably ‘lead’ compounds from natural origin include the alkaloid morphine from poppy, quinine from the cinchona tree and colchicine from meadow saffron. Most of these plants have been screened for their antioxidant and immunomodulatory activities. Some striking results showed that the screened plants could boost the immune system and scavenge free radicals, thus ameliorating numerous diseases caused by oxidative stress. This chapter discusses the antioxidant and immunomodulatory activities of Cameroonian medical plants.