Petiveria alliacea (Phytolaccaceae) is a small shrub which grows in Africa and tropical America, where it is popularly known as “tipim”, “tipi” and “guine”. The leaves are used in folk medicine as diuretic, sedative or analgesic. Phytochemical investigation led to the identification of eight compounds, six of which are being described for the first time in this species: stigmasterol, stigmastenol, stigmastanol, loliolide, 3-hydroxy-5,6-epoxy-β-ionone and benzyl-β-glucopyranoside. The hexane and dichloromethane fractions presented good antitumor activity besides low toxicity. The compounds isolated from the above mentioned fractions were also tested and showed good antitumor activity, which confirms a significant potential of steroids as antitumor agents. These results indicate the potential of P. alliacea as source of antitumor agents.