Backgrounds : As obesity prevails as an epidemic. diet programs including low-calorie diets are developed continuously. It is generally believed that a low-calorie diet is commonly followed by resting metabolic rate decrease and ultimate weight regain. Ephedra and Evodia are known to have sympathomimetic and anti-obesity effect. Objectives : This study was a prospective, double-blinded, randomized md placebo-controlled clinical trial to evaluate the effects of Ephedra sinica and Evodia rutaecarpa on resting metabolic rate (RMR), weight, body composition, and short-term safety in obese women on low-calorie diet. Methods : 125 otherwise healthy obese women (body mass Index ${geq};25kg/m^2$) were recruited and randomly assigned to three groups: Ephedra group (n=41), Evodia group (n =45), and placebo group (n=39). Subjects were administered Ephedra extract in capsules (pseudo-ephedrine 31.52mg) or Evodia extract in capsules (evodiamine 6.75mg, rutaecarpine 0.66mg) or placebo capsules as well as participating in a low-calorie diet for 8 weeks, Resting metabolic rate and body composition were measured at baseline,4 and 8 weeks. Basic serum exams were performed to evaluate the short-term safety of the herbs and changes of lipid variables. Results : All three groups showed significant BMI decreases probably due to low-calorie diet. Among them, the Ephedra group manifested most prominent BMI-reducing effect and towered total cholesterol and triglycerides significantly. The RMR was not changed during the 8-week diet in all groups. No significant difference among the groups was found in RMR, either. Stbject with higher RMR than the mean at the baseline showed a tendency to keep their RMR more stable during the diet program. Conclusions : Ephedra with a low-calorie diet was effective in reducing BMI. RMR change was not compensated by herbal medicines. RMR change seemed to be affected rather by constitution and body composition than medicine. Ephedra and Evodia were proven to be safe for sort-term use in herbal form. Especially, Ephedra was effective in lowering total cholesterol and triglycerides during the 8 weeks.