Benzimidazole is a heterocyclic aromatic organic compound which has been an important pharmacophore and privileged structure in medicinal chemistry. Substituted benzimidazoles have considerable interest as compounds with a wide spectrum of biological activity and low toxicity. Benzimidazole derivatives are structurally related to purine nucleoside bases, which allow them to interact easily with the biopolymers of the living systems. Different substituted benzimidazoles have an extensive range of biological activities including: antiviral, antifungal, antimicrobial, antiprotozoal, antiinflammatory, anticancer, antioxidant, anticoagulant, antidiabetic and antihypertensive activities. Infectious diseases are those whose incidence in humans has increased during the past few decades. They cause suffering and death and an enormous financial burden. Antimicrobial drugs have saved the lives of millions of people. However, the dramatic increase in drug-resistant microbes is threatening to reverse medical progress of the past 50 years. Benzimidazoles are very effective compounds with respect to their bacteria inhibitory activity. Biochemical and pharmacological studies have showed that these molecules are effective against various strains of microorganisms. Some benzimidazole compounds inhibit the biosynthesis of ergosterol, required in the cell membrane of fungi and protozoa and a useful target for antifungal drugs. The result of many efforts to develop new molecules for effective antimicrobials reveals that the benzimidazoles are still one of the most versatile class of compounds against microbes.