RESUMEN
Three patients, a 59-year-old woman, a 51-year-old man and a 66-year-old woman presented at a neurological or neurosurgical outpatient clinic after their lives had been drastically affected by behavioural changes. Neither the patients nor their relatives or friends were aware that the behavioural changes may be caused by a medical problem. The cause, a large meningioma, became obvious only after physical symptoms occurred a few years later. The patients recovered after surgery and regretted having made certain decisions with far-reaching repercussions for their lives and families. Behavioural disturbances are seldom due to slowly growing brain tumours, but consultation with a neurologist is recommended if there is any doubt regarding the possibility of somatic causes.