10.22376/ijpbs.2019.10.1.p1-12 Volume 5 Issue 3 2014 (July- September) Traditional knowledge reveals that most of the plants are medicinally important, especially against cancer and tumors. In the present study, plants resistant and susceptible to crown gall were analysed at laboratory level for cytotoxic and antitumor activity to know whether the plants resistant to crown gall has any constituents or compounds that are cytotoxic or anti-tumour against human tumours. Methanolic extract of lessThan i greaterThan Simaruba glauca lessThan /i greaterThan (crown gall susceptible) showed highest cytotoxic activity against brine shrimps at an LC50 of 166.4ppm followed by lessThan i greaterThan Erythroxylum monogynum lessThan /i greaterThan and lessThan i greaterThan Alianthus excelsa lessThan /i greaterThan (crown gall resistant) extracts at LC50 of 172.3ppm and 238.3ppm respectively. We further assessed antitumor activity against the tumors induced by lessThan i greaterThan Agrobacterium tumefaciens lessThan /i greaterThan using carrot disc anti-tumour bioassay. Results indicated that the extract of lessThan i greaterThan Simaruba glauca lessThan /i greaterThan inhibited tumor induction on carrot discs at a lowest concentration of 100ug/ml as compared to the other two plant extract which inhibited the tumour at a concentration of 800ug/ml and above. The overall results indicate a strong cytotoxic and anti-tumour activity in a crown gall susceptible plant, while crown gall resistant plants are comparatively less cytotoxic as well as anti-tumour activity. K S TULSI NAIK, KIRAGANDUR MANJUNATH, SIDDAMADAPPA CHANDRASHEKARAN AND APPANNA V KOPPAD Bioassays, Cytotoxicity, Agrobacterium tumefaciens, Crown Gall tumour Assay. 344-353