The Radiosensitization of nitroheterocyclic compounds on nucleic acid constituent is discussed in this paper. In aqueous solution of 5'-GMP (1×10,-3,M). studies suggest that both nitroheterocyclic compounds N-6 and N-8 are demonstrated as radioseneitizers by raising the release of the inorganic phosphate (P,i,) in the absence of oxygen. The degree of radiosensitization find expression in C. E. R. It is defined as the ratio of the yields of inorganic phosphate in the presence and absence of sensitizer, i. e. C. E. R.=G(P,i,) sensitized/G(P,i,) unsensitized. Studies suggest that the degree of radiosensitization of both compounds N-6 and N-8 decrease with increasing irradiation dose for same sensitizer concentration, and increase with increasing sensitizer concentration for same irradiation dose. The sensitization effect of compound N-8 is superior to compound N-6. The major mechanism of sensitization may be due to the electron transfer from the OH adduct ,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648369&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648371&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648370&type=, to nitroheterocyclics (N-6 and N-8). The hydrolysis of unstable carbonium ion (GMP-OH) lead to the release of P,i,.