Background. Delusions relating to the body, a ready source of informat
ion about the immediate experiences of psychotic patients, have not be
en systematically studied. We attempted an account of the phenomena, l
ooking for differences between diagnostic groupings in the type and la
teralisation of such phenomena, and for evidence of localisation. Meth
od. Somatic delusions elicited at interview with 550 Research Diagnost
ic Criteria-diagnosed psychotic patients were categorised according to
content, and the results were compared across diagnostic groupings. R
esults. Significant differences were demonstrated, both at the level o
f individual delusions and in the nature and overall pattern of such d
elusions. There were also differences between diagnostic groups in the
choice of body parts involved. Among male patients there were signifi
cant differences in laterality between the groups, with schizophrenic
subjects locating abnormal phenomena principally on the left and depre
ssive subjects on the right. A provisional taxonomy of bodily delusion
s was developed. Conclusion. Phenomenological differences between the
psychoses were demonstrated and the results offer some support for cur
rent hypotheses of localisation of brain dysfunction in the psychotic
illnesses.