β-Blockers are prescribed by physicians for many medical reasons (hypertension, long-term prophylaxis of angina pectoris, myocardial infarction, stable heart failure treatment, cardiac arrhythmias, etc.). Although cases of β-blocker poisoning have a low rate of 0.9% among all poisoning cases, they have a high mortality rate. In β-blocker poisoning with high lipid solubility; seizures, respiratory depression, coma, resistant bradycardia-hypotension and shock may occur. Metoprolol, a type of β-blocker, is a selective β1-adrenoceptor antagonist with sympathomimetic effect. It is also reported that metoprolol is the 2nd most commonly prescribed β-blocker after bisoprolol all over the world. This article aims to present a case who took high-dose metoprolol for suicidal purposes and to examine metoprolol poisoning and its treatment in the light of current literature.