Brain pathologies are frequent sources of mental and behavioral disorders. In order to analyze the boundary between neurology and psychiatry, we analyzed all neuropsychiatric consultations seen at the inpatient Neurology, Neurosurgery, Critical Medicine and Neurological Emergencies clinics of the National Institute of Neurology and Neurosurgery of Mexico between 2007 and 2009.A total of 506 neuropsychiatric visits were included, patient mean age was 44.2 years (SD 17 years) 240 patients were female (47.4%). The main neurological disorders for which patients sought medical care at the neuropsychiatry service, were: brain tumors (14.2%), viral encephalitis (8.7%), ischaemic cerebrovascular disorders (7.1%), epilepsy (6.5%) and haemorragic cerebrovascular disorders (4.7%). The most common DSM-IV psychiatric diagnoses included: delirium (38.5%), depressive disorders (15%), dementia (7.7%), cognitive decline, without fulfilling criteria for dementia (6.5%), and anxiety disorders (6.9%). Delirium was the most common neuropsychiatric condition among the etiological groups. Catatonic syndrome was more frequent among patients with brain infections (p < 0.001), and pathological laughter and crying were more frequent among atients with cerebrovascular disorders (p = 0.012).Our study highlights the clinical relevance of delirium, depression, anxiety, dementia, frontal syndromes and catatonia among neurologic and neurosurgical in-patients attending a tertiary care reference center in Mexico.