Hemiarthropalsty (HA) for proximal femur fractures (PFF) has shown good results in the elderly patient population. It has also been used to treat fractures of the proximal femur in patients with metastatic bone disease (MBD). Nonetheless, complications still occur in both patient populations and their effect on 90-day costs can be a great burden to the healthcare system. Thus, the purpose of this study was to evaluate and compare the outcomes and costs of HA for PFF in patients with bone metastasis versus those without it. The Medicare standard analytical files were queried through International Classification of Diseases and Related Health Problems, ninth edition (ICD-9) codes. A case-control study comparing PFF in patients with and without MBD treated with HA was performed. Medical and surgical complications, mortality, discharge disposition, and length of stay were analyzed and compared. Outcomes were tracked for the 90-day period after surgery. Statistical analysis was performed through odds ratios, unpaired t-tests, and chi-squares. Patients treated with HA for fractures with MBD have higher rates of medical complications compared to fracture patients without MBD. Mortality was found to be significantly greater in the MBD cohort (8.8% vs. 2.3%), as were medical complications and length of stay. Both charges and reimbursements were also significantly greater in the MBD cohort. Patients who undergo hip HA for MBD are at increased risks of medical complications compared to patients who undergo HA for fractures without metastasis, and surgeons should be aware of these increased risks.