The title compound, C27H27N5O3.H2O, is built up from pyrazolinone, phenyl and acetophenone oxime moieties. The 2-phenyl substituent is nearly perpendicular to the pyrazolinone ring, with a dihedral angle of 87.66 (1)degrees. The acetophenone oxime moieties are twisted out of the pyrazolinone-ring plane by 47.04 (1)degrees. The molecules in the crystal pack in an antiparallel fashion and are held together by hydrogen-bonded water molecules and intermolecular O - H ... O and O - H ... N hydrogen bonds.