4-Bromo-o-phenylenediamine and ethylimido-p-bromophenylacetate, 1, were subjected to microwave irradiation to synthesize benzimidazole derivative, compound 2. Ester derivative, 3, and hydrazide derivative, 4, of compound 2 were also synthesized, respectively. Finally, compound 4 was treated with 11 different aromatic aldehydes to obtain benzimidazole derivatives containing imine function. All reactions were carried out with microwave irradiation and conventional heating, and results were compared. Some of the newly synthesized compounds showed moderate antimicrobial activity against some tested organisms.