Ma-huang (Ephedra sinica) is frequently prescribed for obesity management in oriental medicine. The main component is ephedrine alkaloids which can have serious adverse side effects such as heart attack, stroke, sudden death. There are no scientific guidelines for Ma-huang usage in the safe treatment of obesity in oriental medicine. We reviewed published studies on its safety to make evidence based guidelines. Methods : We searched electronic databases up to May 2006. We limited evidence to controlled trials for efficacy or safety, case reports for safety, and studies for Ma-huang contents analysis. Results and Conclusions : In clinical trials for weight loss, Ma-huang and ephedrine promote modest short-term weight loss but have no serious adverse effects, have only a few adverse effects associated with increased risk of psychiatric, autonomic, gastrointestinal symptoms and heart palpitations. In case reports, there have been serious adverse effects including stroke, heart attack, and death using typical doses of ephedrine or no associated illness. There are factors related to serious adverse effects, such as overuse, lack of standardization, individual sensitivity, and interactions with other drugs. Studies relating to these factors should be analyzed for safe use of Ma-huang and ephedrine. After analyzing related studies, we suggest guidelines for Ma-huang usage. We propose that the dosage should be within 4.5-7.5g per day for up to 6 months for generally healthy individual. It`s use is contraindicated in individuals with heart disease, thyroid disease, diabetes mellitus, hypertension, psychiatric disorders, glaucoma, urination disorders, enlarged prostate, persons using MAOIs, methyldopa and sympathomimetic agents.