In the title coordination polymer, [La(C5HN2O4)(H2O)2]n, the lanthanum(III) metal centre is nine-coordinated, with a distorted tricapped trigonal prismatic geometry, by the O atoms of two water molecules and by two N and five O atoms of two N,O-bidentate, one O,O′-bidentate and one O-monodentate 3,5-dicarboxylatopyrazol-1-ide ligands. The polymeric three-dimensional structure is stabilized by intermolecular O—H⋯O hydrogen bonds.