The Alarm Tree Study infers all possible combinations of events that lead to the alarms in a plant. Among the tree cuts, it is possible to isolate those that are minimum; keeping out the cuts which contain other cuts; in other words, redundancies, being an excellent method for the study of the factors that could cause an undesirable event (alarm). It finds its better application in the study of complex situations, moreover, it supplies a method to determine the causes of an alarm. It is a graphic model that makes use of several combinations of system events and human action, that may result in an alarm.