Technical Abstract: Electron micrographs of stained collagen fibrils display a pattern of alternating light and dark bands perpendicular to the axis of the collagen fibril. Light bands correspond to regions of more dense lateral packing where adjacent collagen monomers overlap, and dark bands correspond to 'gap' regions, domains of low-density molecular packing. Most studies of artificially stabilized collagen focus on crosslinks that utilize specific amino acid side chains, without considering whether these are more likely to be located in overlap or gap regions. The gap region with its lower molecular density, greater length, and available telopeptides appears promising as an area able to accommodate oligomeric compounds that are the typical tanning agents. This study uses the ERRC collagen microfibril model to explore the interactions of catechin, a model for vegetable tanning agents thought to interact with serine residues, in the collagen microfibril. Attempts at placing catechin near serine residues in the overlap region were not successful. Four catechin molecules were docked near serine residues in the gap region of the microfibril and subjected to conditions typical of tanning. Under these conditions each catechin molecule moved into a position where stabilizing bond formation was likely, although not with serine. The method will be valuable in predicting the effectiveness of proposed new tanning agents.