AbstractComputer‐assisted measurements were made on the computed tomography (CT) scans of 14 patients meeting ICD‐9 diagnostic criteria for late paraphrenia, seven of whom had exhibited one or more first‐rank symptoms during their illness. When the CT scans of all 14 late paraphrenics were compared with those of an age‐matched healthy control group, there were no significant differences with regard to planimetric measurements of brain and ventricle areas. Comparison of the scans of late paraphrenics with first‐rank symptoms and those without them demonstrated that late paraphrenics without first‐rank symptoms had a greater degree of cerebral atrophy, which was significantly so for the left frontal lobe. The findings support the observation that late paraphrenia is a heterogeneous condition which is comprised of a group with first‐rank symptoms who probably represent late‐onset schizophrenia and a group without first‐rank symptoms who have structural brain abnormalities and a presumed organic substrate for their symptoms that is impossible to exclude through cl