14568 Background: Evidence for preventing androgen deprivation (AD) induced osteoporosis with bisphosphonate therapy in prostate cancer patients has emerged largely from trials conducted in caucasian patients. Osteoporosis related skeletal event incidence in African Americans (AA) receiving AD is significantly lower than caucasians and the effect of bisphosphonates therapy uncertain. We conducted a prospective study to evaluate the efficacy of zoledronic acid in preventing osteoporosis in racially diverse population receiving AD. Methods: Asymptomatic, prostate cancer patients (16 caucasians and 6 AA) with normal renal function undergoing AD, started within the last 9 months were randomized to receive (Arm A) CaCO3/vitamin D (500 mg/200U TID) or (Arm B) CaCO3/vitamin D and zoledronic acid (4 mg IV every 3 months for a year). Bone turnover markers including urine N-telopeptide, serum osteocalcin, serum bone specific alkaline phosphatase(BsAP) were serially measured every 3 months and bone mineral density (BMD) measured by DXA at hip, femur, spine and ward’s triangle at 0, 6 and 15 month intervals. Primary endpoint was to obtain BMD changes and bone turnover rates for each treatment arm. Nonparametric methods for analyzing longitudinal data were used to compare DXA-derived BMD measures and bone turnover rate markers in patients receiving zoledronic acid to the control group. Results: Data is presented for 16/22 patients who have completed 15- month follow up. Time trend analysis of bone formation (BsAP, osteocalcin) and resorption (N-telopeptide) markers and DXA measurements of BMD (spine and hip) are shown in the table. Conclusions: This study suggests that zoledronic acid preserves BMD at spine in racially diverse patients and, likewise provides preliminary estimates of BMD changes that occur over 15 months in patients receiving zoledronic acid and placebo. Larger AA cohorts are needed for prospective validation of the observed effect with zoledronic acid. [Table: see text] [Table: see text]