Despite extensive researches and pre-market clinical trials, only limited information on the adverse drug reactions (ADRs) of a drug can be collected at the time of market approval from regulatory agency. ADRs constitute a major public health problem. Post-marketing surveillance of drugs is important to detect signals for ADR. In Korea, one of the main methods for monitoring the safety of marketed drugs is spontaneous reporting system of suspected ADRs. Re-examination and re-evaluation system are in force for monitoring safety of new market approval drugs and currently under marketing drugs, respectively. Recently, regional pharmacovigilance centers were designated from Korean Food and Drug Administration for facilitating ADR surveillance. Over recent years, with the development of information technology, there has been an increased interest in establishing data mining system for detecting signals from Health Insurance Review Agency database. The purpose of this paper is to review the current status of Korean ADR surveillance system and suggest the possible solutions for developing active pharmacovigilance system in Korea.