The radiation resistance of Bacillus sp. T61 and protein changes after exposure to gamma-ray irradiation were assayed by survival evaluation, two-dimensional gel electrophoresis and mass spectrometry. The results showed that D10 value of strain T61 was 10%, much higher than that of radiation sensitive E.coli K12. Thirty-four proteins showed significant changes after irradiation of 10 kGy, including crucial components participating in antioxidant defense, nucleotide metabolism, energy production, transcription, and protein translation or turnover. The induction of key components involved in antioxidant defense system strongly suggests that antioxidation protection plays a crucial role in radiation resistance in Bacillus sp. T61.Cited