Technetium-99m-kethoxal-bis(thiosemicarbazone) complex (99mTc-KTS), a potentially useful radiopharmaceutical for cholescintigraphy, is prepared by the reaction of KTS with 99mTcO4- in the presence of SnCl2. Under the described conditions, a complex extractable with organic solvent was detected. TLC, electrophoresis, and spectrometric analysis indicate the formation of an uncharged 99mTc(IV) complex. Organ distribution and biliary excretion studies in rats are described. The complex showed a marked highly reproducible accumulation in the gallbladder.