Abstract: Objective: To compare the response and adverse reactions of aminoglutethimide with that of femara, an oral aromatase inhibitor, in postmenopausal women with advanced breast cancer.Methods: Fifty patients were randomly assigned to femara 2.5mg once daily (n =26) or aminoglutethimide (n=24) 125mg twice daily in the first week, 250mg twice daily in the second week, 250mg tri daily in the third week, 250mg quadri daily in the fourth week, thirty days for one cycle. Results:Overall objective response rate (complete Npartial) of 26.9% for femara was higher than 12.5% for aminoglutethimide, but there was no significant difference (P =0.294). Stable disease were 53.8% and 50.0%, respectively, in both treatment groups. Progressive disease were 19.2% and 37.5%. There were no significant difference between two arms in the receptor status, disease-free intervals, sites of disease and stages of treatment. Femara-related adverse events were fatigue (15.4%), anorexia (11.5%), dizziness (7.7%), nausea (3.8%), headache (3.8%) and somnolence (3.8%). Nausea (25.0%) and vomiting (16.7%) in aminoglutethimide were obviously higher and severer than femara (P=0.045 and P=0.046) >Dizziness (25.0%), fatigue (20.8%), anorexia (16.7%), somnolence (12.5%) and cutaneous pruritus (12.5%) were more frequent, and allergic rash occurred in one patient with aminoglutethimide. Conclusion: Femara was effective and well tolerated than aminoglutethimide with respect to side effects in the treatment of postmenopausal women with advanced breast cancer.