[Brugada syndrome and early repolarization syndrome]. Brugada syndrome (Brugada sign) and early repolarization syndrome (ERS) are two relatively recently defined ECG findings that raise the suspicion of dangerous cardiac arrhythmia. In this review, we focus on the clinical relevance of these ECG findings, describe them and provide a detailed explanation of their electrophysiological mechanisms, based on the published data. We hope this provides a better understanding of the underlying physiological substrate. Brugada sign is a rare finding, but is associated with increased risk of sudden cardiac death. On the other hand, early repolarization syndrome is a more frequent ECG finding in many healthy people and not usually associated with increased risk of cardiac arrhythmia. Several reports have demonstrated that early repolarization syndrome may be associated with significant malignant arrhythmic events, including ventricular fibrillation, in certain subgroups of patients. Recently, it was reported that Brugada syndrome and early repolarization syndrome have a genetic link, so mutations in SCN5A and KCNE1 are suspected to be the underlying mechanisms. In this review, we summarize the available data of the two ECG diagnoses, especially genetic studies. In conclusion, Brugada sign and early repolarization syndrome are two rare ECG findings in healthy people. Brugada sign seems to be strongly associated with malignant arrhythmia, and early repolarization syndrome is associated with increased risk of sudden cardiac death in certain subgroups of patients. Genetic studies of the mechanisms of the disease are in progress. However, their role in practice is not yet defined. The future of this exciting field of electrocardiography is very bright.