To study the possibility of radioactive labelled vasoactive intestinal peptiede （VIP） for tumor VIP receptor imaging. 125I-VIP was prepared by chloramine-T method

and purified by sephadex G-50 column chromatography. The bioactivity and stability of 125I-VIP were measured by silica 60 F254 TLC and competition test to SGC7901 cell in vitro. The biodistribution of 125I-VIP was studied in the nude mice bearing tumor. The results showed that labelled rate of 125I was 73.8%

the specific activity was 18.2PBq/mol

the radiochemical purity（RCP） was over 98% and remained 96.3% after 48 days stored at m80oC. The specific binding of 125I-VIP to the SGC7901 cell was inhibited by VIP in dose dependence in the competition experiment. The radioactivity of tumor was higher than that of muscles in all phases （P<0.05-0.01）

the peak activity of tumor occured at 30min （3.58 ± 0.48ID%/g） and the peak ratio of T/N occured at 60min after the injection. The activity of lungs was obviously higher than that of blood

the intestine was always in low level. Most of the activity in the body was mainly eliminated from kidney. The present study demonstrated that the radioactive labelled VIP is a promosing agent for tumor VIP receptor scintigraphy.