In the title compound, C11H12N2O2·C4H4O4·H2O, the l-tryptophan molecule crystallized as a zwitterion, together with a neutral fumaric
acid molecule and a water solvent molecule. In the crystal, the three components
are linked by a series of N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds, forming slabs lying
parallel to (001). The slabs are connected by O—H⋯O hydrogen bonds, involving inversion-related
fumaric acid groups, leading to the formation of a three-dimensional structure.