Objectives : The aim of this study is to evaluate the safety of acupuncture therapy when applied to patients who are undergoing anticoagulants / antiplatelet medication therapy combined with herbal medicine using a retrospective, case-control study. Methods : 428 charts of patients were reviewed in this study. Odds ratio between case of bleeding-related adverse event and control was calculated as main analysis. Exposures were anticoagulants / antiplatelet medication, Hwalhyeolgeoeo herbal medicine and combination of both drugs. Additionally, odds ratios were calculated according to the severity of bleeding-related adverse events. Results : The results were as following: 1. Analysis of all bleeding-related adverse events showed there was no increased risk of combined therapy compared with other exposures and control group. 2. Analysis of only clinically significant adverse events showed there was no increased risk of combined therapy compared with other exposure and control group. 3. Hwalhyeolgeoeo herbal medicine group showed a tendency of increased risk of bleeding-related adverse events in all analysis but was not statistically significant. Conclusions : The results suggest that Hwalhyeolgeoeo herbal medicine-anticoagulant / antiplatelet medication combined therapy may not increase risk of bleeding-related adverse events in acupuncture therapy. By executing various modules of analysis, it was possible to acquire useful data for possible future studies. Further research is needed to confirm such results.