Abstract: Cancer and some other mutation-related diseases are still remained among the most difficult ones of clinical aspects. Regards to the mention issue attention is drawn to dietary anti-mutations as cancer preventative agents. The presence of anti-mutagenic agents in medicinal plants such as Zataria multiflora, Achillea wilhelmsii and Camellia sinensis can be considered due to their antioxidants properties. So, in the present work, different fractions of these plants were assessed for their anti-mutagenic effects using Ames method. Aerial parts of the tested plants after collection, drying and milling were extracted using petroleum ether, chloroform and 80% methanol consecutively by percolation method. The dried extracts under vacuum were examined for their anti-mutagenic effects. The minimum inhibition concentration (MIC) of the extracts was evaluated by ager dilution method. Various concentrations under their measured MIC were used for anti-mutagenic test. Each extract along with bacterial strain and mutagen agent were incubated at 37°C for 48 h. The number of revertant colonies was counted and compared with control plates. Our results showed that all fractions of Z. multiflora exhibited anti-mutagenicity effect in the presence of TA98, while only its methanolic fraction was active against TA100. Methanolic and chloroform fractions of C. Sinensis showed strong anti mutagenicity against TA98 only, while the methanolic fraction of A. wilhelmsii showed anti-mutagenicity effect in the presence of both TA98 and TA100. Considering the presence of flavonoids in methanolic fraction and high antimutagenicity effect of this fraction, flavonoids are probably responsible for anti-mutagenic effect of the plants.