In the title compound, also known as N-carbamoyl-l-proline, C6H10N2O3, the pyrrolidine ring adopts a half-chair conformation, whereas the carboxyl group and the mean plane of the ureide group form an angle of 80.1 (2)ampersand-flag-changedeg;. Mol-ecules are joined by N - H⋯O and O - H⋯O hydrogen bonds into cyclic structures with graph-set R 2 2(8), forming chains in the b-axis direction that are further connected via N - H⋯O hydrogen bonds into a three-dimensional network.