This report discusses the importance of pharmacovigilance (PV) in contributing to building up resilient health systems. It is based on and summarizes the findings of a review of available literature on the topic and relevant case studies focusing on a set of country and regional experiences. Although indispensable in improving health outcomes, the administration and use of medicines may produce adverse reactions, requiring continuous monitoring to ensure that the benefits outweigh the risks. PV, which involves the systematic detection, reporting, assessment, understanding, and prevention of adverse drug reactions (ADRs), is an essential public health function, but it is often overlooked. The goals of PV are to improve patient safety through the timely detection of previously unknown ADRs that are revealed to be associated with medicines during post marketing surveillance; promote the safe use of medication; enhance public health through the appropriate use of medication; contribute to the assessment of benefits, harm, effectiveness, and risks of medicines; and encourage the safe, rational, more effective, and cost-effective use of drugs. The recent Covid-19 pandemic has highlighted the value of PV in building resilient health systems that respond well during a public health crisis and in normal times.