Abstract:Radon 222 released from rocks contribute to the level of radiation in human body. The stratigraphy of West Java, which is dominated by granite, has a high level of radon. The result of the study in Padalarang shows that the highest dose of radon is 24 Bq/kg and the lowest 17 Bq/kg. The alpha rays may affect the Superoxide Dismutase (SOD) level. The research is conducted on all men and women in the age of 30 to 70 living in Padalarang district who met the inclusion criteria, with good general health condition, being original inhabitant since birth, not suffering from chronic systemic infectious diseases, and willing to participate in the research by completing the informed consent. Sample is taken by using consecutive sampling. Blood sample is taken as much as 2 cc/person by using a 2cc syringe, which is then inserted into venoject tube containing heparin. Antioxidant activity in the blood plasma is examined by using SOD Kit. The average of SOD level is 3.56 ui/ml in Highland (Masigit Mountain) and 1.65ui/ml in lowland (Cipatat). The increase of SOD level of the people living in Highland is suspected to be the contribution of radon exposure contained in rocks and water.