Chloride ion channels vary from many other ion channels due to being controlled by the anionic chloride ions. Chloride ion channels are pore-forming membrane proteins that allow the passive transport of chloride ions across biological membranes. Chloride ion channels involve both voltage-gated and ligand-gated mechanisms to transport the ions across cellular membranes. Chloride ion channels have been found to play crucial roles in the development of human diseases, for example, mutations in the genes encoding chloride ion channels lead to a variety of deleterious diseases in muscle, kidney, bone, and brain, including cystic fibrosis, osteoporosis, and epilepsy, and similarly their activation is supposed to be responsible for the progression of glioma in the brain and the growth of malaria-parasite in the red blood cells. Currently, chloride ion channels are not completely understood, and more research is necessary.