The objective of the surveillance systems of vaccine adverse events is monitoring events temporally related to vaccination, to evaluate their causality with the vaccine and to detect events after the introduction of new vaccines. The ultimate goal of these systems is to provide the population with the best safety standard of the vaccines. The surveillance system can be passive (spontaneous reports) or active (active follow up of vaccinees); the majority of them are passive. The article gives a brief review of the most known vaccine adverse events surveillance systems, including the American Vaccine Adverse Events Report System (VAERS), the Canadian and European systems, a commentary about the Chilean one, highlighting its main advantages and also its limitations.