Objective : To evaluate the effect of Ephedra Sinica and Evodia Rutaecarpa on resting metabolic rate(RMR), weight and body composition in obese women during low-calorie diet. Methods : We recruited 90 healthy premenopausal women(body mass index.25kg/m2) and randomly assigned to three groups(ephedra group, evodia group and placebo group). Subjects were administered Ephedra Sinica(6g twice a day) or Evodia Rutaecarpa(6g twice a day) or placebo in a double-blind fashion and participated in low-calorie diet for 8 weeks. Resting metabolic rate and body composition were measured at baseline, 4 and 8 weeks. Results : RMR change for 4 weeks was significantly higher in the ephedra group compared with the placebo group(p<.05). But the change for 8 weeks was not significant and the Evodia group showed no significant RMR change. Weight and percent body fat changes for 4 weeks and 8 weeks were significantly higher than the placebo group in the ephedra group(p<.05), but the Evodia group didn`t show significant level. Conclusions : This study supports and emphasizes the benefits of herbal medicine in maintaining or increasing RMR during low-calorie diet. Especially Ephedra treatment was effective on significant maintainment of RMR, loss of weight and percent body fat(P<.05).