Abstract: The aim of this study is to explore the method of radiolabeling lipiodol with ¹⁸⁸Re and to appraise the quality of the product. Lipiodol was labeled with ¹⁸⁸Re directly at the temperatures from 75 ℃ to 120 ℃ with different reaction conditions. The time-variation labeling efficiency was measured to evaluate the stability of ¹⁸⁸Re-lipiodol.The molecular structure change caused by radiolabeling was analyzed with infrared spectrometer. The embedding effect of lipiodol was explored by SPECT imaging of bearing cancer S180 mice. The optimal condition was obtained with the labeling efficiency over (99.1±0.4) %. More than (90.9±1.9)% and (92.8±1.2)% of radioactivity was kept in lipiodol form in room temperature and in 37 ℃ human plasma for 3 d. Infrared spectrum imaging shows that the molecular structure of radiolabeled lipiodol is unchanged. SPECT imaging of S180 tumorbearing mice testifies the radioactivity concentrated in tumor for 48 h after injection of ¹⁸⁸Re-lipiodol. The directly radiolabeling method is easy to operate, and the labeling efficiency is higher than (99.1±0.4)%. The radiolabeled product is stable for 72 h, and the embedding effect of lipiodol to ¹⁸⁸Re is well. ¹⁸⁸Re radiolabeled lipiodol can be used for further investigation.