The aims of RADAR are to disseminate safety reports for serious adverse drug reactions and to identify barriers to identification and reporting of these events. Investigators have developed a well-coordinated system to accurately compile case report information on sADRs and to identify milestones associated with identification and reporting of the relevant ADR information. This ADR identification system allows us to amass pertinent sADR information from a diverse set of data sources in order to identify and report sADRs in a timely and thorough manner. The RADAR methodology relies on initial recognition of these "sentinel" cases that then prompts hypothesis–driven inquiries as to whether an unrecognized adverse drug event signal is present in the patients exposed to that drug. Hypothesis-driven active surveillance of small but thorough sets of safety reports serves as the underlying conceptual framework of RADAR pharmacovigilance. Fewer than 20 individual ADR reports led to RADAR investigators identifying safety signals for the majority of the ADRs described to date.The success of the RADAR program has been largely based on the use of diverse data sources to identify, clarify, and verify ADRs.