The adverse drug reaction(ADR) monitoring is very critical in healthcare. However, the number of actual reported cases on ADR has been extremely low in Korea compared to other countries. This study was designed to find out a way to expedite ADR reporting in a general hospital, where many drugs are used daily. In this study, a newly developed ADR monitoring system has been implemented and was evaluated for its outcome. In addition, a survey was conducted for two groups, 50 ADR reporters and 100 non-reporters, to identify factors which can affect the ADR reporting. The new system was a multidisciplinary program based on a voluntary reporting involving doctors, nurses and pharmacists. The reporting methods were diversified such as ADR report sheet, computerized Order Communication System(OCS) consultation and drug refund reports. After a year since the system has been implemented, the number of reported cases was 158, which was 131 times higher than that of the pre-implementation period. Doctors reported the most(75 .3%), and ADR report sheet was used most frequently(57%). In terms of severity of ADR 74.7% was mild, 22.8% moderate and 2.5% severe. The unexpected ADRs were 7.6%. Both groups had a high degree of awareness of the necessity of monitoring and basic knowledge of ADR. Important factors affecting ADR reporting were frequency of ADR findings(p<0.01), awareness of the fact that the institution was designated as an ADR monitoring institution(p<0.001) and participation in the education program(p<0.01). In conclusion, modification of the reporting system and ongoing and systematic education are needed to improve ADR monitoring in a general hospital.