Antineoplastic activity against human gastric and colon carcinoma cell lines was measured in 49 extracts from 46 plants using MTT (3-[4, 5-dimethyl thiazol-2-yl]-2, 5-diphenyl tetrazolium bromide) method. Six extracts from five plants have been reported to have antineoplastic effect. Extracts from remaining 41 plants failed to show significant cytotoxic effect at the concentration of less than $230;{mu}g/ml$.