Objectives : The aim of this study was to systematically investigate herbal-drug-associated adverse drug reactions (herbal ADRs) reports submitted by a single oriental hospital and to analyze the general characteristics, causative agents, clinical manifestations, severity and types of herbal medicines which caused herbal ADRs. Methods : This study proceeded with IRB approval. The data on herbal ADR were collected prospectively from January 2008 to February 2012 by EMR of Dongguk University Ilsan Oriental Hospital. The World Health Organization (WHO)-Uppsala Monitoring Center (UMC) criteria was used to determinate causality for each herbal ADR. WHO-Adverse Reaction Terminology (WHO-ART) System Organ Class (SOC) code and WHO severity category were also used in this study. Results : A total of twenty eight cases were reported. Twenty two cases were assessed to have over possible relations with herbal medication. The gender ratio of these cases were 64.6 percent female and 36.4 percent male, demonstrating no statistical significance. Patients aged over 60 were 59.1%. Gastro-intestinal system was reported to be the most frequently affected organ (38.8%), and followed by psychiatric system (22.4%), and integumentary system (22.4%). The most common clinical symptom was headache (12.2%), followed by diarrhea (10.2%), and pruritus (10.2%). The severity of most cases was assessed to be mild (89.8%). The percentage of moderate ones was 10.2%, and there were no severe cases. Conclusions : Progressive study and further analysis on herbal ADRs are warranted for safety in the clinical use of herbal medicines.