Recently, because of the rising in multidrug resistance from infectious agents, there is a prompted interest for the development of new antimicrobial agents and new therapeutic strategies to combat the infections caused by the resistant bacteria. Among them, the natural bactericidal compounds, such as antimicrobial cationic peptides (AMPs) seems very promising agents. AMPs are the important component of the innate immune response to the surrounding microorganisms. These substances which can be isolated from most of the living organisms, have various activities, like broad spectrum antibacterial, antifungal, antiviral, and antiprotozoal. However there are some resistance mechanisms that affect the AMPs, because of the rapid action and existing more than one mechanism of action, development of resistance to AMPs is quite rare. Due to their many advantages and characteristics, AMPs looks like a good candidate for being a new generation, active antimicrobial agents for antimicrobial chemotherapy against especially multi drug resistant bacteria and biofilms, either alone or in combination.