In the title compound, C17H16N2O3, the seven-membered diazepine ring adopts a boat conformation with the hy­droxy-substituted C atom at the prow and fused benzene ring C atoms at the stern. The phenyl substituent occupies an equatorial position. The amino group of the ring system is a hydrogen-bond donor to the oxo O atom of an inversion-related mol­ecule, and the hy­droxy group is a hydrogen-bond donor to the acetyl O atom of another inversion-related mol­ecule. The two hydrogen bonds generate a ribbon motif parallel to [10] in the crystal structure.