Objective To investigate the changes of serum copper in mice after whole-body irradiation and analyze the feasibility of these changes as a biological dosimeter.Methods Serum copper in mice exposed to 60 Co γ-rays(0,1,2,3,5 Gy) was collected from the orbital of mice and detected with 5-Br-PADAP colorimetric method at 30 min and 7 d after radiation.One-way analysis of variance was used to analyze the difference of serum copper in each group and Dunnett-t test was used to compare the difference between control group and irradiated groups.Linear and quadratic linear fitting function was used to analyze the relationship between serum copper and radiation dose.The change of serum copper was detected at 30 min,1,3,5,7,10,13 and 16 d after radiation to observe the persistence of serum copper.The established relationships were used to estimate the dose in 8 mice irradiated by a blind dose.Results The amount of serum copper in irradiated mice were significantly (F =208.20,145.98,P ＜ 0.05)dependent on the radiation doses with dose responses of y =-0.091x + 0.936 and y =-0.011x2-0.032x + 0.962 (r =0.989,0.995) at 30 min and 7 d post-irradiation,respectively.The concentration of serum copper at 2.0 Gy decreased at 30 min post-irradiation,increased at 1-7 d,then kept at a stable level at 7-14 d even increased slightly after 14 d.With these dose response curves,after radiation with a blind dose of 2 Gy,the absorb doses of mice were assessed to be (1.83-2.25) Gy and (1.82-2.11) Gy at 30 min and 7 d in 95％ confidence interval,respectively.Conclusions The serum copper is a quick,simple,and sensitive biomarker for the early assessment of absorb dose of irradiated mice.