Bombesin (BBN), a 14 amino acid peptide, is an analogue of human gastrin releasing peptide (GRP) that binds to GRP receptors (GRPr) with high affinity and specificity. The GRPr is over expressed on a variety of human cancer cells including prostate, breast, lung, and pancreatic cancers. The specific aim of this study was to identify a BBN analogue that can be radiolabeled with 1 7 7 Lu and maintains high specificity for GRPr positive prostate cancer tumors in vivo. A preselected synthetic sequence via solid phase peptide synthesis (SPPS) was designed to produce a DOTA-BBN (DOTA = 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) conjugate with the following general structure: DOTA-X-Q-W-A-V-G-H-L-M-(NH 2 ), where the spacer group, X = ω-NH 2 (CH 2 ) 7 COOH (8-Aoc). The BBN-construct was purified by reversed phase-HPLC (RP-HPLC). Electrospray Mass Spectrometry (ES-MS) was used to characterize both metallated and non-metallated BBN-conjugates. The new DOTA-conjugate was metallated with 1 7 7 Lu(III)Cl 3 or non-radioactive Lu(III)Cl 3 . The 1 7 7 Lu(III)- and non-radiolabeled Lu(III)-conjugates exhibit the same retention times under identical RP-HPLC conditions. The 1 7 7 Lu-DOTA-8-Aoc-BBN[7-14]NH 2 conjugate was found to exhibit optimal pharmacokinetic properties in CF-1 normal mice. In vitro and in vivo models demonstrated the ability of the 1 7 7 Lu-DOTA-8-Aoc-BBN[7-14]NH 2 conjugate to specifically target GRP receptors expressed on PC-3 human prostate cancer cells.