e18165 Background: Intravenous bisphosphonates (IV BP) reduce the risk of skeletal-related events in patients with multiple myeloma (MM). However, data describing racial differences in utilization of IV BP in non-clinical trial settings is limited. In this study, we evaluated population-level IV BP utilization and factors associated with initiation and discontinuation of IV BP therapy. Methods: We conducted a retrospective cohort study of patients aged 65 years or older diagnosed with first primary MM between 2001 and 2011. Patients were identified using the Surveillance, Epidemiology and End Results (SEER)-Medicare linked database and followed through December 2013. Patients were required to have Medicare Parts A and B coverage and patients with end-stage renal disease were excluded. Treatment with anti-MM therapy (chemotherapy and/or proteasome inhibitors) were treated as time-dependent variables. We analyzed cumulative incidences of IV BP initiation from the diagnosis of MM for all patients and separately time to discontinuation from IV BP initiation. In multivariable Fine and Grey models accounting for competing risks, we estimated subdistribution hazard ratios (SHR) and 95% confidence intervals (CI) for initiation and discontinuation. Results: 14,231 eligible patients had a mean [median] age of 76.8 [76] years and 51.8% were male. During a median follow-up of 23.1 months, 53.7% of patients received at least one intravenous bisphosphonate (IV BP) administration. IV BP initiation, duration and treatment frequency differed between racial groups. Among white patients, 64.4% of IV BP were administered every 4 weeks, compared to 59.3% in African Americans, 62.7% in Hispanic, and 64% in Asians. In multivariable models, Black patients experienced a significant delay in IV BP initiation (SHR 0.75, 95%CI 0.70-0.80) and were more likely to have early discontinuation (SHR 1.08, 95%CI 1.00-1.17). Conclusions: Despite recommended therapy with IV BP for MM patients, approximately half of older patients did not receive the therapy, with a significant lag experienced among racial minority groups. Efforts to improve uptake of IV BP and continued management of therapy in minority groups are needed. [Table: see text]