Many proteins are present in oligomer forms. For example, majority of transport proteins can form oligomers, and notable protein oligomers are amyloid- protein oligomers, which are early symptoms of Alzheimer’s disease (AD). Ebola virus proteins and HIV integrase are all oligomers. When ligand(s) approach a protein oligomer, interactions can cause the binding properties to change with each ligand molecule bound. Special ligands can be designed to cause the oligomeric protein to significantly reduce activity towards a target ligand. This property has been exploited for human health. In this presentation, the mechanism and principles behind the ligand-protein oligomer interactions are discussed and some of its applications are presented.