A novel class of antimicrobial polymeric agents, which include a plurality of amino acid residues, such as positively charged amino acid residues, and at least one hydrophobic residue linking there between. such as an omega-amino-fatty acid residue designed to exert antimicrobial activity while being stable, non-toxic and avoiding development of resistance thereto and a process of preparing same are disclosed. Further disclosed are pharmaceutical compositions containing same and a method of treating medical conditions associated with pathological microorganisms, a medical device, an imaging probe and a food preservative utilizing same. Further disclosed are conjugates of an amino acid residue and a hydrophobic moiety residue and a process of preparing same.