The rationale for setting up the WHO International Programme for Adverse Reaction Monitoring, 30 years ago was to make it possible to identify rare adverse drug reactions (ADRs) that could not be found through clinical trial programmes. It became evident that maintaining an international database of ADR case reports and a network of institutions and scientists concerned with drug safety issues provides great additional gains when compared with operating in isolation. Thus, the scope of the WHO programme has expanded over time to accommodate the expansion of the field of drug safety monitoring, now often named pharmacovigilance. The international centre, the WHO Collaborating Centre for International Drug Monitoring in Uppsala [now known as the Uppsala Monitoring Centre (UMC)], maintains the international database and serves the national centres associated with the WHO programme; however, the role of the centre is expanding allowing it to play a leading role in global drug safety monitoring. The national centres are appointed by the governments of each of the countries participating in the WHO programme. These centres are responsible for collecting spontaneous ADR reports originating from health professionals, 49 countries are currently contributing case information and are full members of the programme; an additional 11 countries have applied for membership but have still not submitted any reports. The annual influx of reports is currently fluctuating at around 150,000 reports. In its development, the data collected by the WHO programme was guarded by strong rules of confidentiality. In some member countries, however, case data, with the important exception of reporter and patient identities, has always been public information. The UMC has made it a priority to try to create an atmosphere of openness and trust between all parties involved in drug safety assessment, which will eventually enable general sharing of available data and an extended analysis and use of the data collected. The WHO network represents the wealth of competence and experience that is at the disposal of countries wishing to join the international pharmacovigilance community.