Objective This study is designed to assess the cost of services provided to Medicare beneficiaries by nurse practitioners (NPs) billing under their own National Provider Identification number as compared to primary care physicians (PCMDs). Data Source Medicare Part A (inpatient) and Part B (office visit) claims for 2009–2010. Study Design Retrospective cohort design using propensity score weighted regression. Data Extraction Methods Beneficiaries cared for by a random sample of NPs and primary care physicians. Principal Findings After adjusting for demographic characteristics, geography, comorbidities, and the propensity to see an NP, Medicare evaluation and management payments for beneficiaries assigned to an NP were $207, or 29 percent, less than PCMD assigned beneficiaries. The same pattern was observed for inpatient and total office visit paid amounts, with 11 and 18 percent less for NP assigned beneficiaries, respectively. Results are similar for the work component of relative value units as well. Conclusions This study provides new evidence of the lower cost of care for beneficiaries managed by NPs, as compared to those managed by PCMDs across inpatient and office‐based settings. Results suggest that increasing access to NP primary care will not increase costs for the Medicare program and may be cost saving.