The aim of this study was to determine the frequency and etiology of altered mental status in adults at an Emergency Department. Medical records of 790 patients with altered mental status were reviewed. Out of 790 patients, 414 (52.3%) were male, 376 (47.7%) were female. Mean age was 45.65 +/- 15.5 years. Etiologic factors were neurological (n = 566; 71.6%), head trauma (n = 82; 10.4%), endocrine/metabolic (n = 48; 6.1%), cardiovascular/pulmonary (n = 49; 6.2%), infectious (n = 30; 3.8%), gynecologic and obstetric (n = 2; 0.4%), toxicologic (n = 12; 1.5%). Of patients, 40% were in deep coma, 11% were confused, 20% were in agitated confusion, 15% were lethargic, and 14% were in stupor. Eighteen percent of were hypertensive. Total mortality rate was 20.1% (n=159). Common causes of death were cerebrovascular disease and trauma. Most patients presenting with altered mental status seem to be elderly with the most frequent cause being cerebrovascular accidents. Fatality rate is very high.