Twenty healthy adult fingernails were collected, water rinsed, and irradiated with 137Cs γ-rays. EPR spectra were measured before and after exposure. The results show that the radiation-induced signal (RIS) in fingernails was relatively stable after the 10th day, and the background signal(BS) of the cut fingernail was gradually increased within 68 d; when fingernails were irradiated less than 15 Gy dose, RIS signal intensity increased with the dose in the first 8 d. The influence of intrinsic signals must be considered in dose reconstruction. Fingernail EPR method can be used for rapid screening of irradiated population after nuclear accidents.Cited