Introduction: Although cancer patients with acute altered mental status (AMS) often present to the emergency department (ED), there is lack of documentation for survival in ED cancer patients with related causes of ANIS (structural or metabolic causes). The aim of this study was to evaluate reasons for acute AMS of cancer patients in the ED and their prognostic value for survival. Methods: Medical records of cancer patients presenting to ED with acute AMS were reviewed. Patients were divided into 3 groups with respect to AMS etiologies: metabolic causes (Group1), structural causes (Group 2) and both (Group 3). Median survival time was calculated from the ED presentation and Kaplan-Meier survival curve was generated to demonstrate survival in the three groups. Results: Forty-nine patients had only metabolic causes of AMS (Group 1), 21 of whom had more than one metabolic abnormality. Forty-six patients had only structural causes (Group 2) and 7 had both metabolic and structural causes (Group 3). Survival probability at one month was 33% for all patients, 25% for Group 1,48% for Group 2 and 0% for Group 3 (p=0.11). In Group 1, 32% of patients with only one metabolic disorder and 14% of those with more than one metabolic disorder were alive at one month (p=0.197). Conclusions: Regardless of aetiology, cancer patients presented with AMS to the ED usually have poor outcomes. Survival in our ED cancer patients with AMS is not related to the either structural or metabolic causes of AMS.