A simple and practical protocol was developed for the synthesis of benzimidazoles. The protocol uses iminoester hydrochloride which is very useful in the reaction with 4,5-dichloro-1,2-phenylenediamine under microwave irradiation leading to the products with good yields and in short reaction times. This method can be used as a general technique for synthesizing benzimidazoles. The synthesized compounds were evaluated for their biological properties such as anti-lipase, antiviral, and antitumor activities. Five benzimidazol-1-acetic acid hydrazides showed slight antiviral activity at 25 mu g/cm(3) concentration despite their low toxicity. Substituted 2-benzylbenzimidazoles were active against adenocarcinoma (CT26) and melanoma (B16F10) cancer cell lines at concentrations below 10 mu g/cm(3). Six of the compounds showed anti-lipase activities at various concentrations; the IC50 value of one compound was 0.35 mu g/cm(3), which is similar activity to that of orlistat (0.32 mu g/cm(3)).