Abstract: OBJECTIVE: To establish dose-response relationship between prematurely condensed chromosome (PCC) rings of human peripheral lymphocytes and neutron radiation. METHODS：Heparinized peripheral blood was taken from two healthy adult females and irradiated by 0，1.0，2.5，5.0，7.5 and 10.0 Gy of neutron (dose rate 0.2 Gy/min). Blood was kept in incubator (37 ℃) for 3 h for cell repair. Then blood was cultured with RPMI 1640 for 48 hrs. 1 hr before the end of culture，Okadaic acid，at final concentration of 500 nmol/L， was added into culture medium to induce PCC rings. Yield of PCC rings at each dose point after staining with Giemsa was counted and the relationship between PCC rings of human peripheral lymphocytes induced by neutron radiation was examined. RESULTS：In 500 nmol/L Okadaic-acid-induced prematurely condensed chromosomes of human peripheral lymphocytes， the yield of PCC rings increased with the dose of radiation and showing a linear correlation (y=0.097 6x+0.000 3， R2=0.980 5). CONCLUSION： A good dose-response relationship was found between the yield of PCC rings and radiation dose from 0 to 10 Gy. The yield of PCC rings could be used as a biodosimeter in neutron irradiation，especially for high dose.

Key words: neutron, biodosimeter, peripheral blood lymphocytes, prematurely condensed chromosomes