The triazoloquinazole fused-ring system of the title compound, C(10)H(7)ClN(4)O(2)S, is essentially planar (r.m.s. deviation = 0.009 Å). In the methyl-sulfonyl substituent, the two S-O bonds are of equal length [1.402 (2) Å]. In the crystal, adjacent mol-ecules inter-act weakly through Cl⋯N contacts [ca 3.197 (2) Å].