The construction of heterocyclic systems including pyrrolone (lactam) and fused imida-/oxa-/thiazolidine fragments is quite relevant due to the broad spectrum of biological activity exhibited by these molecules. In this work, crystal structure and the structural features of 8a-phenylhexahydropyrrolo[1,2-a]pyrimidine-6(2H)-one, C13H16N2O, are reported. Titled compound crystallizes with Z = 4 in the space group P21/n with cell volume of 1109.6(4) Å3 [a = 6.0910(13) Å, b = 17.016(4) Å, c = 10.707(2) Å, β = 90.581(5)°]. Molecules in the solid state are weakly linked by the intermolecular hydrogen bonds C=O···H–N into the chains.