The crystal structures of three guanidinium hydrogen dicarboxylate systems are solved by X-ray diffraction methods and discussed with respect to similarities and dissimilarities of their hydrogen-bonded networks. The basic crystal chemical units in all of them are extended into ribbons, which are further organized in monolayers. However, the symmetry relations inside the layers vary from crystal to crystal and essentially depend upon the aliphatic spacer between the two carboxylic groups. Both the one- and the two-dimensional hydrogen-bonded networks in crystal 1 are polar and both are non-polar in crystal 2, whereas in crystal 3 the ribbons are polar but the monolayers are non-polar.