Iron is a trace element of considerable interest to both chemistry and biology. In a biological context its chemistry is vital to the roles it performs. However, that same chemistry can contribute to a more deleterious role in a variety of diseases. The brain is a very sensitive organ due to the irreplaceable nature of neurons. In this regard regulation of brain iron chemistry is essential to maintaining neuronal viability. During the course of normal aging, the brain changes the way it deals with iron and this can contribute to its susceptibility to disease. Additionally, many of the known neurodegenerative diseases have been shown to be influenced by changes in brain iron. This review examines the role of iron in the brain and neurodegenerative diseases and the potential role of changes in brain iron caused by aging.