The ADR reporting systems applied worldwide, which are most commonly known and can be taken as an example, are described as a general overview. More precisely, the descriptions refer to: "Voluntary Reporting System" and "Prescription Event Monitoring"--UK; FDA regulations and "Boston Collaborative Drug Surveillance Program"--USA; "Centre Regional de Pharmacovigilance"--France. The experience in the North Countries and Japan is also briefly illustrated. Furthermore, initiatives taken by the Council of International Organizations of Medical Science (CIOMS) and by the WHO are mentioned. This short overview highlights that the Health Authorities in the most advanced Countries have shown an ever growing attention for ADR reporting, and the regulations in every Country take into special consideration the serious and the unforeseen adverse reactions, as well as their recurrence.