Abstract: Adverse events following immunization, while rare, unfortunately do occur. And when they do, the public''s faith in vaccines waves. It''s a known fact, for example, that vaccine safety concerns are among the most important factors contributing to parents refusing vaccination for their children. How best, then, to tackle these concerns and increase public confidence in the vaccine safety system? In an effort to contribute to identifying the right mechanisms, the International Alliance for Biological Standardization organized an international symposium on "Post-Licensure Evaluation of Vaccine Safety" in Barcelona in early Spring. Delegates from 24 countries took a close look at the current status of this challenging problem and identified several practical measures which could help address the situation. They suggested an integrated vaccine safety program to be in place in all countries and standardized so that information and data can be exchanged on a routine basis. Another proposal was to put in place simple measures such as the use of bar codes on vaccine vials. [Copyright &y& Elsevier]