This study addresses in vitro effects of raspberry (Rubus idaeus) seed extracts (RSE) on the frequency of micronuclei. We evaluated the effects of three different extracts (50%, 80%, and 100% methanol) in doses of 1.4, 4.2, and 8.4 microg/mL, per 5 mL culture using cytochalasin-B micronucleus (CBMN) assay in peripheral human lymphocytes. The frequency of MN was scored in binucleated (BN) cells. The nuclear proliferation index was also calculated. The distribution of polyphenolic compounds in RSEs was determined using LC/UV/ESI-TOF MS. The identified 37 compounds comprised flavanol monomers and oligomers, as well as varieties of ellagitannin components. Treatment of lymphocytes with RSEs induced a significant decrease in the frequency of micronuclei by 80%. These results demonstrate that the constituents of RSEs may be important in the prevention of oxidative lymphocyte damage by reactive oxygen species and may also reduce the level of DNA damage. These findings support the potential benefits of polyphenolic compounds from raspberry seeds as efficient antioxidants.