Tc-99m labeled PnAO(propylene amine oxime) derivatives have been widely studied as brain perfusion agents. We synthesized and characterized a PnAO derivative, (RR/SS/meso)-4,8-diaza- 3,9,dimethylundecane-2,l0-dione bisoxime(PRODD). Proton-NMR spectroscopy and thin layer chromatography(silence gel) were performed for its characterization PRODD was 1abeled with Tc- 99m using stannous chloride as reducing agent. The labeling efficiency was determined to be about 85%. Brain uptakes of 4.16¡¾0.42 %ID/g and 3.24¡¾0.13 %ID/g were found after l0min and 30min after intravenous injection. Brain-to-blood ratios were 1.17 and 0.75 at 10 and 30 minutes, which were lower than 1.3 and 1.9 of the ratios with commercial Tc-99m-HMPAO. Autoradiographs of rat brain sections showed the gray matter to white matter ratios of 1.13¡¾0.10 at 30 min after intravenous injection, which was lower than 1.94¡¾0.19 of commercial Tc-99m-HMPAO. With the above findings, we concluded that the lipophilic Tc-99m-PRODD complex was able to cross the blood-brain barrier, however the complex showed lower uptake than Tc-99m- HMPAO in mouse or rat brains. We Could suggest possibility that PRODD could be used as another Tc-99m chelator.