Effects of mutations of Pprl (Dr0167) and RecX (Dr1310), which are relative to radioresistance, on reactive oxygen species scavenging activities in Deinococcus radiodurans were investigated using gene mutation, chemiluminescence measurement and enzyme activity analysis. Their possible regulating functions on the activities of antioxidant enzymes was evaluated. Results show that mutant that lacks PprI is remarkably sensitive to reactive oxygen species and its enzyme activities of catalase and superoxide dismutase decrease significantly. On the other hand, RecX has a "negative" effect on reactive oxygen species scavenging activities of this bacterium, i.e., mutation of recX enhances the scavenging activities on reactive oxygen species, and the enzyme activities of catalase and superoxide dismutase in mutant that lacks RecX are significantly increased. These results indicate that these two genes are relative to the regulation of antioxidant system of this bacterium. It presents some idea to the further investigation on the antioxidant mechanism of this bacterium.