Aim To create and validate a simple scoring system for predicting 30-day mortality in patients presenting with acute coronary syndromes (ACS) at their moment of admission.Methods and results 2407 consecutive patients presenting to Harefield Hospital with measured arterial blood gases, from January 2011 to December 2020, were studied to build the training set. 30-day mortality in this group was 17.2%. A scoring algorithm that was built using binary logistic regression of variables available on admission was then converted to an additive risk score. The resultant scoring system is the BE-ALIVE score, which incorporates the following factors:Base Excess (1 point for