Abstract: Tc m\|YDPC is prepared by Schwartz method. In vitro immunoreactive fraction and associate constant are measured by Lindmo , s method and Scatchard method respectively. 14.4 MBq 99 Tc m\|YDPC is injected into nude mice bearing human PC\|3M prostate cancer. The labeling yield of 99 Tc m\|YDPC is up to 41%～65%. The immunoreactive fraction and associate constant of 99 Tc m\|YDPC to prostate cancer cell line PC\|3M is 58.1% and 7.71×10\+9 L/mol respectively. The radioactivity ratio of tumor over non\|tumor tissues(T/NT) is greater than 2.00 except that of tumor over blood and lung 22 h post injection and is higher than that of control group. The results indicate radioactivity concentration on tumor site in nude mice bearing prostate cancer but no radioactivity concentration on colon tumor. The investigation demonstrates that 99 Tc m\|YDPC has an excellent immunoreactivity and tumor locating property, and the radiolabeled YDPC may be useful for the diagnosis or therapy of prostate cancer.\;