Objectives. Determine the prognosis at three months and associated factors of patients with altered mental status (AMS). Materials and methods. Cross-sectional study that included patients over 18 years of age admitted to the emergency room in a national hospital, with AMS, within twenty-four hours of onset and that required observation. The demographic, clinical and functional assessment information were taken from the medical record. A follow-up was made at three months by telephone. Results. The study included 290 patients, representing 4.1% of the total patients in the emergency room. Overall mortality was 24.2%, whereas in the subgroup of older adults was 28.1%; 19.3% in adults and 15.2% in young adults. The average age was 63.5 years and the elderly group constituted nearly two thirds of the population. 51% were males. The average hospital stay was 7 days. The most frequently associated causes were infectious diseases (44.1%), neurological (40.3%), respiratory (28.3%), metabolic (18.6%), and cardiovascular (17.2%) disorders. Mortality was associated with a) GCS levels <7 (OR 2.9, p[removed]