In the title compound, C(26)H(21)N(3)O(3)S, the quinazolinyl group is essentially planar [r.m.s. deviation for the 10 non-H atoms = 0.057 Å]. The isoindoline-1,3-dione group is linked by an SCH(2)CH(2) chain to the pyrimidinyl C atom that lies between the two N atoms. Also, the phenyl group is linked by a CH(2)CH(2) chain at the N atom adjacent to the carbonyl group. This results in a conformation with these substituents lying to either side of the central quinazolinyl unit, with the former being approximately parallel [dihedral angle = 4.93 (7)°], and the phenyl group being inclined [dihedral angle = 71.61 (9)°] to the central quinazolinyl fused-ring system. In the crystal, mol-ecules are consolidated into a three-dimensional architecture by C-H⋯O inter-actions, involving all three carbonyl-O atoms, and π-π inter-actions occurring between the pyrimidinyl and isoindole-benzene rings [inter-centroid distance = 3.5330 (13) Å].