This paper aims to evaluate the in vitro anticancer activity of aqueous extract of Abrus precatorius l eaves on the murin mastocytoma cancer cell line (P815), and the phytochemical analysis of the extract as well. The Aqueous extract (ETA), was obtained by traditional method a dapted to laboratory conditions and the phytochemic al analysis was based on differential staining and precipitation reaction s. In vitro anticancer effect was evaluated by the cellular cytotoxicity against the murin mastocytoma cell line (P815). Cellular cytotoxicity was determ ined by the MTT assay. Phytochemical screening of aqueous extra ct showed several chemical groups: alkaloids, flavo noids (flavones), tannins, coumarins, sterol, triterpenoi ds, saponins and reducing compounds. The in vitro a nticancer effect, showed a dose dependant cytotoxic effect. I t was observed, that the maximum activity of the ex tract at the highest concentration tested (200μ g/mL) was 50% (±1 .5). Further on lower doses of 3.12; 6.25; 12.15; 2 5 and 50 μ g/mL percent growth inhibition observed by the ext ract was between 43 and 47 %, the IC50 value of the extract (200μ g/mL. Our results suggest that aqueous extract of A. precatorius leaves contains several chemical groups and possess a weak in vitro anticancer effect against P 815 tumor cell line.