"Despite of the recent advances in the structural investigation of complex molecules, the comprehension of the 3D features responsible for the interaction between opioid peptides and micro-opioid receptors still remains an elusive task. This has to be attributed to the intrinsic nature of opioid peptides, which can assume a number of different conformations of similar energy�" -Gentilucci, L. and A. Tolomelli (2004). Recently, we had an interesting observation: morphine, the well-known natural opioid receptor ligand, appears to closely mimic the backbone of opioid peptides (See the picture below). In this presentation, the related supportive materials will be discussed. Hopefully, this observation can serve as a novel clue for the active conformations of opioid peptides.