The novel 2-[(E)-2-aryl-1-ethenyl]-3-(2-sulfanyl-1H-benzo[d]imidazole-5-yl)-3,4- dihydro-4-quinolinones (4a-j) analogs were synthesized by Knoevenagel condensation of a solution of 2-methyl-3-(2-sulfanyl-1H-benzo[d]imidazole-5-yl)-3,4-dihydro-4-quinazolinone (3) with aromatic aldehyde in presence of catalytic amount of piperidine. Compounds (4a-j) showed significant biological activity against all the standard strains. All the synthesized compounds were characterized on the basis of their IR, 1H NMR, MASS spectroscopic data and elemental analyses. All the compounds have been tested for antimicrobial and antifungal activity by the cup-plate method.