Although Social Phobia has been recognised for centuries in comparison with other anxiety disorders, relatively little work has been done to understand its neural basis. The present review attempts to redress this balance by giving an overview of the current state of knowledge in this disorder. By putting together data from the treatment responses to specific agents, the effects of chemical challenges which have been used in other anxiety disorders and by reviewing data on central and peripheral neurotransmitter and endochrine abnormalities, it is possible to begin to generate some potentially testable theories of aetiology and mechanisms. Finally, we review the potential use of neuroimaging techniques to better detail the brain circuits and possibly neurotransmitters involved in social phobia, showing some of our preliminary work using (15)O water blood flow PET activation studies to determine the brain circuits in which metabolism is changed during the experience of social anxiety.