The anticarcinogenic properties of some commonly consumed spices and leafy vegetables were investigated. The effects of feeding the plant products on the induction of squamous cell carcinomas in the stomachs of Swiss mice by feeding benzo[a]pyrene(B[a]P) and on the induction of hepatomas in Wistar rats by feeding 3'-methyl-4-dimethylaminoazobenzene (3'MeDAB) were investigated. Among the nine plant products tested, cumin seeds (Cuminum cyminum Linn) and basil leaves (Ocimum sanctum Linn) significantly decreased the incidence of both B[a]P-induced neoplasia and 3'MeDAB-induced hepatomas. Poppy seeds (Papaver somniferum Linn) significantly inhibited B[a]P-induced neoplasia alone, while the other plant products, asafoetida, kandathipili, turmeric, drumstick leaves, solanum leaves and alternanthera leaves were ineffective. These results suggest that cumin seeds, basil leaves and to a lesser extent poppy seeds, which are all widely used in Indian cooking, may prove to be valuable anticarcinogenic agents.