The mol-ecule of the title compound, C(13)H(9)NO(2), is slightly twisted with a dihedral angle of 4.85 (9)° between the nine-membered ring system and the phenyl ring. The nine non-H atoms of the 1H-pyrrolo[2,1-c][1,4]oxazin-1-one system are coplanar [r.m.s. deviation = 0.0122 (2) Å]. In the crystal, weak inter-molecular C-H⋯O inter-actions link mol-ecules into chains along [10]. The crystal studied was an inversion twin with a 0.48624 (9):0.51376 (9) domain ratio.