A series of 3-[4'-(4-aryalazo)-3, 3'-dimethoxy-biphenyl-4-yl]-2-phenyl-3H-quinazolin-4-one derivatives (3) have been obtained by a reaction of a various coupling agent (a-o) with diazonium salt containing 4-oxo-quinazolin moiety (2). The diazonium salt (2) is obtained by the reaction of 4-(2-phenyl-4-oxo-3-quinazolinyl)-4'-amino-3, 3'-dimethoxydiphenyl with NaNO 2 and HCl. The proposed constitutions of newly synthesized molecules have been supported by elemental and spectral analysis. The products exhibit promising dyeing capabilities.