In the course of routine autopsy examinations at the Western Washington State Mental Hospital during a two year period, thirty cases of intracranial tumor were found, giving a percentage incidence of 13.5. This figure is so much higher than that of any previously reported study that it cannot be regarded as the true incidence of intracranial tumor in mental hospital populations. The author has no adequate reason to offer for the occurrence of so many intracranial growths in this series of autopsies. No far-reaching conclusions can be based upon such a small group of autopsies (223). Needless to say each case was most carefully studied but this has also been done by many competent examiners on much larger series of mental hospital autopsies. It is hoped that this report will stimulate more thorough and careful analysis of the types and frequency of intracranial tumors in these patients.The tumors were classified as to type utilizing modern neurohistologic techniques and neuropathologic classification. Meningiomas were the commonest type of neoplasm encountered, a finding which coincides with previous reports upon this subject. Gliomas were much less frequent than in the series of cases compiled in general hospitals.Abstract Teaser