Polyamines are essential for the growth and survival of all cells with biosynthesis and transportation of polyamines being very active in tumors. With the aim of developing a new tumor imaging agent, three artificial synthetic polyamine analogs, diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA), were labeled with 99m Tc. The 99m Tc-labeled complexes were characterized by TLC and studied for stability.99m Tc-DETA, 99m Tc-TETA, and 99m Tc-TEPA were formed in high yields and found to be stable.99m Tc-DETA, 99m Tc-TETA, and 99m Tc-TEPA revealed high tumor uptakes of 0.65, 0.58, and 0.59% ID/g at 4 h pi, respectively, in HepA tumor-bearing mice. The ratios of the tumor to the contralataral muscle (T/CM) were 13.68, 5.99, and 9.81, respectively. SPECT images revealed clear visualization of tumors. Excretion routes were mainly through urine and feces. The tumorto-muscle count density ratios of 99m