The crystal structure of 1-allyl-5-(4-methylbenzoyl)-4-(4-methylphenyl)pyrimidine-2(1H)-thione (C 22 H 20 N 2 OS) has been determined from three dimensional single crystal X-ray diffraction data. The title compound crystallizes in the monoclinic space group P2 1 /c, with a = 10.6674(13), b = 10.1077(7), c = 17.9467(19) Å, β = 98.460 (9) o , V = 1914.0(3) Å 3 , D calc = 1.251 g cm -3, Z = 4. In the title compound, the allyl group shows positional disorder. Molecules are linked by C-H···O, C-H···N and C-H···S intermolecular interactions forming two-dimensional network.