OBJECTIVES: The use of herbal products continues to expand rapidly across the world. The concerns of safety of herbal products have been raised. Health Product Vigilance Center (HPVC) database (Thai Vigibase) is the national existing health products surveillance system which can be used to detect signal of adverse events (AEs) in patients receiving herbal products. This study aims to describe and characterize reported AEs in patients receiving herbal products in Thailand. METHODS: Thai Vigibase data from February 2000 to December 2008 involving AEs of reported herbal products were included. The database contained patients' demographic, AEs associated with herbal products, seriousness, causality and quality of reports. Descriptive statistics were used for data analyses. RESULTS: A total of 593 reports with 1868 AEs were reported during the study period. The age range of reported cases was 1 to 86 years (mean, 47 years). Female patients were frequently reported (72%). Reports involving turmeric were most frequently reported. Gastro-intestinal problems were the most common clinical outcomes among herbal products associated with adverse events. Severe adverse events such as Stevens Johnson syndrome, anaphylactic shock and exfoliative dermatitis were also found. CONCLUSIONS: HPVC database is a potentially effective tool for herbal adverse events monitoring. Encouraging reporting can contribute to improve awareness among health personnel and patients about the benefit-harm profile of the herbal products.