ABSTRACT: The prices that insurers pay physicians ultimately affect beneficiaries' health insurance premiums. Using 2014 claims data from three major insurers, we analyzed the prices insurers paid in their Medicare Advantage (MA) and commercial plans for 20 physician services, in and out of network, and compared those prices with estimated amounts that Medicare's fee-for-service (FFS) program would pay for the same service. MA prices paid by those insurers were close to Medicare FFS prices, varied minimally, and were similar in and out of network. In contrast, commercial prices paid by the same insurers were substantially higher than FFS, varied widely, and were up to three times higher out of network than in network. Those results suggest that insurers can use statutory limits on out-of-network charges in MA to negotiate lower in-network prices in those plans. In contrast, without those limits on out-of-network prices, in-network prices in commercial plans are much higher.