Delusions are commonly thought of as bizarre and fascinating; a delusion is a false belief that is held despite counterevidence. They have also been hard to study, in part because of the many forms that they can take. In recent decades, neuroimaging techniques have made it possible to study delusions more empirically, by using methods such as Single-photon emission computed tomography (SPECT) and Magnetic resonance imaging (MRI) to locate neural correlates. The Capgras delusion is a syndrome in which a patient has the belief that someone has been replaced by an impostor. The Cotard delusion is a syndrome in which a patient has the belief that oneself does not exist or is dead. These two delusions have been found to have some curious similarities. This thesis investigates how the Capgras and Cotard delusions relate to each other, with a focus on the neural correlates. The nature of delusions is explained, along with the Capgras and Cotard delusions. Relevant case reports for each delusion are presented. Neural correlates are also reviewed and compared between the delusions. Studies on the similarities in face recognition impairments are included, as well as on attribution styles. The findings demonstrated in this thesis show that the Capgras and Cotard delusions relate to each other in several ways, including in terms of overlapping neural correlates, in face recognition impairments, attribution styles and the fact that both delusions sometimes co-exist and follow each other. It is possible that the Capgras and Cotard delusions share fundamentally similar causes.