Starting and developing an effective pharmacovigilance (PV) system based on reporting adverse effects of medicines and vaccines is a well-recognized way to improve patients safety. Notwithstanding this, the size and complexity of Brazil has presented particular challenges in developing and consolidating an effective pharmacovigilance (PV) system, with lessons and experiences that may be of particular interest. It has 212 million inhabitants,1 ranking as the sixth most populated country and its population is very diverse. Geographically, it is the largest country in Latin America and fifth in the world, after Russia, Canada, the United States, and China. Furthermore, Brazil is a federative republic organized in 26 states and is classified as an upper-middle-income country.According to the 1988 Federal Constitution and several Laws (Leis 8.080/90 and 8.142/90), Brazilian healthcare management and policies depend on a decentralized but integrated system involving the central government, the states and the municipalities. In practice, this means that the responsibilities of the healthcare sector are distributed between the three government levels.In August 2001, Brazil became the 62nd country admitted to the World Health Organization Program for International Drug Monitoring (PMID). But, as in many other countries, pioneering work to monitor the safety of medical treatments actually started long before. Once the Brazilian Health Surveillance Agency (Portuguese: Agência Nacional de Vigilância Sanitária, ANVISA) was created and deployed, PV in Brazil became a harmonized program covering all 26 states, using a common reporting form and, since 2018, a common database (VigiMed).As of February 2022, VigiMed contained more than 98,000 reports of suspected adverse drug reactions collected since 2018. The leading state in reporting volume is São Paulo (accounting for 20 percent of all Brazilian reports).2