To study the radioiodinating condition of interleukin-8(IL-8) and observe its biodistribution in mice for understanding the possibility of its application in nuclear medicine, we labelled IL-8 with 125I using Bolton-Hunter reagent, and the distributions in mice at 5 min, 30 min, 1h, 6h and 24h after injection of 125I -IL-8 were measured.The blood clearance curve was obtained and fitted with the two-compartment model. The results showed that 125I-IL-8 was obtained with a labeling efficiency of 12.2% ±6.5% and a radiochemical purity of 91.4%±6.5%. Its specific activity was 14.8 kBq/μg IL-8. A fast phase half- life T1/2aof 0.32 h and a slow phase half- life T1/2β of 8.01 h were calculated from the blood clearance curve. The uptakes of radioactivities in kidneys and lung had the peaks of 85.87%ID/g and 16.17%ID/g at 30 min after intravenous injection, respectively. The uptakes in liver and spleen were 12.05%ID/g and 8.97%ID/g as the maximum at 5 min after injection. The clearance in blood and other organs was fast. Except for kidneys and lung, 125I -IL-8 was less than 1%ID/g 24 h after administration. It is concluded that radioiodinated IL-8 is a promising radiopharmaceutical in nuclear medicine, especially for imaging infection. But to enhance the labeling efficiency of radioiodinated IL-8 and to decrease its in vivo deiodination are the subjects necessary to be further investigated.