Measurements were carried out to investigate the potentialities of gamma back-scattering technique in detection of hidden contrabands such as codeine (C18H21NO3) and cannabis (C21H30O2). This is done using an assembly consisting of 241Am gamma source, producing about 5×107 photon.s-1, in conjunction with a NaI(Tl) detector. The source-detector distance was optimized and the optimal configuration was selected. The results in terms of contrast ratios and Figure of Merit verified the feasibility of utilizing the proposed system in detection the targeted samples when sealed in a plastic cylindrical cane. The high contrast ratios achieved; 25% for codeine and 11% for cannabis verified the good distinction ability of the device.