The intracranial tumors found at autopsy in 2,161 mental patients are reported. This group represents 96.9% of all patients who were autopsied at the Western State Hospital during the 16-year period from October 1, 1938, to October 1, 1954. Seventy-eight intracranial tumors were found for an incidence of 3.6%. The incidence of the various kinds of intracranial tumors found is discussed. These incidences are compared with reports of similar autopsy series in both mental and nonmental patients. The data examined reveal a significantly higher incidence of intracranial tumors and of meningiomas in mental patients than in nonmental patients. The greater incidence of meningiomas in mental patients is partly responsible for the greater incidence of intracranial tumors in this group. Meningiomas are frequently asymptomatic and may only appear to be more frequent in mental patients since at autopsy the brain is routinely examined whereas in autopsies of nonmental patients the brain is frequently left undisturbed. Thus many asymptomatic meningiomas in nonmental patients are overlooked at autopsy. Against this are observations that meningiomas frequently produce only psychiatric symptoms. Thus patients harboring one of these tumors tend to gravitate to psychiatric hospitals and not to general hospitals or neurosurgical units.Abstract Teaser