The aim of this study was to investigate the safety of short-term use of Korean herbal medicine (KHM; prescribed herbal medicine by doctors of traditional Korean medicine) on liver function. Three hundred eighty four outpatients who took KHM for various conditions were enrolled for multi-center, prospective observational study. Of them 237 patients completed questionnaire and were checked liver function (aspartic aminotransferase;AST, alanine aminotransferase;ALT, alkaline phosphatase;ALP, total bilirubin;t-Bil, direct bilirubin;d-Bil, gamma glutamyltranspeptidase;GGT, protein and albumin) before and after taking KHM (duration; 21.4${pm}$10.0 days), and data were analysed statistically. Of the 213 patients showing normal liver function test (LFT) at baseline, 209 (98.1%) remained within the normal range at the second test while 3 (1.4%) revealed slight increase of LFT. Only one subject had raised LFT regarding level of liver injury without perceived symptoms. Twenty-four of 237 patients were abnormal at baseline, and 16 at the second testing. Of the patients taking KHM, only 4 changed from normal to abnormal while 12 from abnormal to normal in their LFT. There were no significant increase in LFT level between the first and second test, except in the t-Bil level, however, the change of t-Bil was small and within normal range. The current study showed that the use of KHM did not increase the frequency of abnormal LFTs, at least in the short term.