The present study was carried out to assess the antitumor effect of the ethanol extract of Phallusia nigra against S-180 bearing adult Swiss albino mice. The results showed significant, dose dependent decrease in tumor volume, packed cell volume, viable cell count, increase in non viable cell count and mean survival time there by increasing the life span by 85.31% in group IV treated with 150 mg/kg body weight. Administration of the extract restored the hematological parameters near to normal when compared to those treated with standard drug.