The delta polymorph of sulfanilamide (or 4-aminobenzenesulfonamide), C(6)H(8)N(2)O(2)S, displays an overall three-dimensional hydrogen-bonded network that is dominated by a two-dimensional substructure with R(2)(2)(8) rings; these result from dimeric N-H...O interactions between adjacent sulfonamide groups. This study shows how the polymorphism of sulfanilamide is linked to its versatile hydrogen-bonding capabilities.