We established a database (using Microsoft Excel 2007) to extract data. The database had two components: 1) general characteristics, including country of first author and number of authors, whether the review had the participation of TCM practitioners, number of trials and participants included, disease, the year of review last assessed as up-to-date, conclusions drawn by the reviewers (by assessing the reviewers' abstract conclusions statements), interventions in experimental groups, number of herbs included, and whether the results of different herbal medicines were pooled; 2) methodological quality of included reviews, including OQAQ scale, the approach to assessment of methodological quality of primary studies, the number of trials with adequate sequence generation and allocation concealment, and type and number of English and Chinese databases searched. Two reviewers (Jing Hu and Wei Zhao) independently extracted the information of each review, disagreements between the two reviewers were resolved by discussion.