The asymmetric unit of the title compound, C(6)H(5)N(3)O, consists of discrete molecules of 9-deazahypoxanthine [systematic name: 3H-pyrrolo[3,2-d]pyrimidin-4(5H)-one]. The structure displays N-H···O hydrogen bonding, connecting the molecules into centrosymmetric dimers. These dimers are then connected by N-H···N hydrogen bonds into a ladder-like chain along the c axis. The secondary structure is stabilized by weak noncovalent contacts of the C-H···O and C-H···C types, as well as by π-π stacking interactions, which organize the structure into a zigzag architecture.