10575 Background: Fulvestrant is shown to be an effective hormonal agent in menopausal hormone-receptor positive metastatic breast cancer (MBC) patients. This study aimed at showing if Ld of fulvestrant will improve its efficacy over the FDA approved Std schedule. Methods: We retrospectively reviewed our pharmacy electronic database over a period of two years to identify MBC patients who were treated with fulvestrant. Patients received either Std of 250 mg IM on day (d) 1 and repeated Q28d or Ld of 500 mg IM d1 and 15 and Std on d28 which was repeated every 28 days until evidence of progression. All medical records were reviewed and responses were recorded as improved disease (ID), stable disease (SD), or progressive (PD) as documented by the treating oncologist. Time to response (TTR) (the interval from first injection until response) as well the duration of response (DR), was determined. Results: Medical records of 157 consecutive, evaluable patients who received F for their MBC were identified and reviewed. Group 1 (Gp1) received std (N = 122) and Group 2 (Gp2) received loading dose (N = 35). There were no significant differences between the two groups in relation to age, pathology, grade, Her-2, ER and PR status or number of prior chemotherapy regimens (p > 0.05). Gp2 had statistically significant more prior hormone therapies (p = 0.0159). Median number of doses for Gp2 was 5 (R: 1–18) compared to 3 (R: 1–25) for Gp1 (p = 0.0169). Responses (ID) 14% for Gp1 and 18% for Gp2; clinical benefits (ID + SD) were 37.7% and 38%, respectively, NSS (p = 0.9550). TTR was 10 (R: 6–32) wks for Gp1 and 8 (R: 4–20) wks for Gp2; the DR was 15.5 (R: 4- 84) weeks for Gp1, and 12 (R: 2- 96) for Gp2. No statistical significance was detected between the 2 groups. Conclusions: This study showed there is no significant difference between the 2 dose schedules, either in the response rate or its duration. Prospective studies are needed to prove the equivalence of the Std and Ld of F. No significant financial relationships to disclose.