Considering the importance of natural products in cancer therapy, a preliminary investigation on some anticancer medicinal plants of north-eastern states of India was conducted in murine tumor model. Nine different plants such as Ageratum conizoides Linn. (Asteraceae), Blumea lanceolaria Linn. (Asteraceae), Dillenia pentagyna Roxb. (Dilleniaceae), Potentilla fulgens Wall. (Rosaceae), Taxus baccata Linn. (Taxaceae), Mirabilis jalapa Linn. (Nyctaginaceae), Xanthium strumarium Linn. (Asteraceae), Dillenia indica Linn. (Dilleniaceae) and Gynura conyza Cass. (Compositae) were studied. Out of these, the ethanol extract of D. Pentagyna showed the most potent antitumor activity, i.e. % ILS ~ 55% and % ILS ~ 48% at a dose of 50 and 100 mg/kg/day, respectively; followed by aqueous extract of P. fulgens showing % ILS ~ 37% at a dose of 50 mg/kg/day. Out of different fraction extracts of D. pentagyna and P. fulgens, better antitumor activity was observed with chloroform extract of D. pentagyna (% ILS ~ 89%) and hexane fraction of P. fulgens (% ILS ~ 37%) at a dose of 50 mg/kg/day. A significantly higher antitumor activity of D. pentagyna and P. fulgens seems to be due to the presence of alkaloids and flavonoids. Further detailed studies on its toxicity as well as isolation and structural elucidation of biologically active principle(s) are required.