Hydrogen bonding is dominating directed noncovalent interaction that is responsible for molecular conformations and molecular aggregation affecting small molecules but also macromolecules. It is the govering parameter in the organisation of molecules in the crystalline state but also in the solution. It contributes to the formation of supramolecular species having different properties to those of the basic building units. Hydrogen bonding also participates in a proton transfer during catalytic activity of enzymes and, in general, hydrogen bonds should be considered as incipient proton transfer reactions. The formation of one-, two- and three-dimensional hydrogen bonded assemblies of modified amino acid derivatives is studied by X-ray structure analysis. Systematic analysis of hydrogen bonding patterns as a function of proton donor and acceptor properties, and sterical parameters will be presented for a large number of bis(amino acid)oxalyl and phthaloyl acid derivatives. Particular attention will be given to the molecular topology of such supramolecular assemblies.