The CRIEPI initiated the Radiation Hormesis Research based on the following rationale. If the Luckey’s claim was true, our daily activities in the radiation management would be extremely erroneous. If the Luckey’s claim was false, the concept publicated would bring us serious disturbance on the radiation management in Japan. We organized a hormesis research steering committee by the specialists in the concerned field, and started researches under cooperation with many universities, National Cancer Center Research Institute, and National Institute of Radioiogical Sciences. After interesting results obtained by various experiments on the health effects by low dose, we are now proceeding on the Round Robin tests program including fifteen research plans with universities all over Japan. These activities are categorized as: A. Effects of free radicals produced by the low dose radiation; B. Molecular biological responses to the low dose radiation; C. Radiation effects on the neurotransmission system; D.Stimula If the Luckey’s claim was false, the concept publicized would bring us serious disturbance on the radiation management in Japan. We organized a hormesis research steering committee by the specialists in the concerned field, and started researches under cooperation with many universities, National Cancer Center Research Institute, and National Institute of Radioiogical Sciences. After interesting results obtained by various experiments on the health effects by low dose, we are now proceeding on the Round Robin tests program including fifteen research plans with universities all over Japan. These activities are categorized as: A. Effects of free radicals produced by the low dose radiation; B. Molecular biological responses to the low dose radiation; C. Radiation effects on the neurotransmissio n system; D.Stimula