The title compound, C5H6ClN3O, is essentially planar with a maximum deviation of 0.0256 (11) Å for all non-H atoms. In the crystal, adjacent mol-ecules are linked by a pair of N-H⋯N hydrogen bonds, forming an inversion dimer with an R2(2)(8) ring motif. The dimers are further linked via N-H⋯O hydrogen bonds into an undulating sheet structure parallel to the bc plane.
* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.