In this study, two carotenoid antioxidants lutein and neoxanthin were investigated for their ability to prevent oxidatively induced DNA damage. AChlamydomonas reinhardtiialga was used as the natural source of lutein and neoxanthin. Analysis using HPLC with Diode Array Detector (DAD) showed that lutein and neoxanthin were the most abundant carotenoids in the extract ofC. reinhardtii. An analysis using GC-MS/MS was performed to measure the damage induced by Fenton reaction to DNA and to evaluate the ability of lutein, neoxanthin andC. reinhardtiiextract to inhibit such damage. The results showed that lutein and neoxanthin have the ability to reduce oxidatively induced DNA base damage to less than half of its magnitude. Extract ofC. reinhardtiiinhibited about 76% of the damage in comparison to control sample. Neoxanthin in lower concentrations than those of lutein proved to be better inhibitor of oxidatively induced DNA damage.