Several studies have shown the antimutagenic DNA protective functions of some naturally occurring phenolic phytochemicals. Emerging research also indicates that synergistic functionality of these phytochemicals in whole foods benefits the management of many diseases. This study investigated the potential antimutagenic properties of cranberry phenolics, ellagic acid (EA), rosmarinic acid (RA) and their synergistic interactions on enhancing the antimutagenic properties in Salmonella typhimurium tester system against the mutagens sodium azide and N-methyl-N'-nitro-N-nitrosoguanidine. The ability of these phytochemical treatments to protect oxidative damage to DNA was also investigated using the supercoiled DNA strand scission assay. The results showed that EA was most effective in inhibiting the mutations in S. typhimurium system, whereas RA and EA were equally effective in protecting the DNA from oxidative damage. In addition, the antimutagenic activity of cranberry powder (CP) made from juice extracts was significantly enhanced when 30% (w/w) of phenolics in CP was substituted with RA and EA, possibly because of synergistic redox modulation that can influence mutagen function. It was also suggested that the synergistic mixture of cranberry phenolics with RA could also be protecting the cell from mutations by modulating the DNA repair systems