PurposeTo ascertain the proportion of all Medicare payments to physicians under the Medicare Physician Fee Schedule (PFS) that is attributable to noninvasive diagnostic imaging (NDI). Materials and MethodsThe Medicare Part B Physician/Supplier Procedure Summary Master Files for 2003 to 2015 were the data source. Total approved payments to physicians for all medical services were determined each year. We then selected all procedure codes for NDI and determined aggregate approved payments to physicians for those codes. Also, Medicare’s provider specialty codes were used to define payments to four provider categories: radiologists, cardiologists, all other physicians, and independent diagnostic testing facilities together with multispecialty groups (in this category, the specialty of the actual provider cannot be determined). ResultsTotal Medicare-approved payments for all physician services under the PFS increased progressively from $92.73 billion in 2003 to $132.85 billion in 2015. In 2003, the share of those payments attributable to NDI was 9.5%, increasing to a peak of 10.8% in 2006, but then progressively declining to 6.0% in 2015. All four provider categories saw the same trend pattern—a peak in 2006 but then decline thereafter. By 2015, the shares of total PFS payments to physicians that were attributable to NDI were as follows: radiologists 3.2%, cardiologists 1.2%, all other physicians 1.2%, independent diagnostic testing facilities or multispecialty groups 0.4%. ConclusionThe proportion of Medicare PFS spending on physician services that is attributable to NDI has been declining in recent years and is now quite small.