The aim of this review is to analyze whether there is a need for scientific information about the beta blocker (BB) rebound phenomenon; whether such information is available; and, if it is, how detailed is the BB rebound phenomenon explained in the guidelines and papers? A narrative review is used due to the lack of valid randomized clinical trials (RCTs) on the topic, which are needed for a meta-analysis. The BB rebound phenomenon can have dangerous consequences. The discontinuation of a BB leads to a fourfold increased risk of events related to coronary artery disease in hypertensive patients; it increases in-hospital mortality in heart failure patients; it can precipitate angina pectoris attack; and it increases the risk for death and rehospitalization in patients who survive acute myocardial infarction. Consequently, being considered in the guidelines, the BB rebound phenomenon is believed to be clinically relevant (by experts in the field). This is in sharp contrast with the lack of any additional relevant information about the BB rebound phenomenon in the various important guidelines. For example, we lack a consensus about the precise definition. Moreover, data about the incidence and optimal prevention strategies are lacking for the phenomenon (which is sometimes life-threatening). The BB rebound phenomenon is an additional reason why it is very important to test the prognosis of patients following the cessation of long-term medicaments in RCTs, particularly for BBs.