This research aims to develop a polymeric drug delivery system for docetaxel (DTX) and to investigate its radiotracer potential by in vitro. DTX loaded Poly(lactic acid)/Poly(ethylene glycol) diblock copolymer (PLA-PEG) was synthesized and radiolabeled with technetium-99m tricarbonyl core. PLA-PEG-DTX nanoparticles had a particle size and zeta potential 120 +/- 7.3 nm and - 24.66 +/- 1.5 mV respectively, which was further supported by SEM image. The radiolabeling efficiency of Tc-99m(CO)(3)-PLA-PEG-DTX was found to be 90 +/- 3.51%,. In vitro study was carried out on cancer cell lines (MCF7, MDA-MB-231) to examine the biological behavior of docetaxel loaded PLA-PEG nanoparticles.