Some orthopedists and neurologists acquired their own magnetic resonance imaging (MRI) equipment during the early 2000s. This paper examines changes in imaging use and in overall spending by patients of orthopedists and neurologists who began billing for MRI scans between 1999 and 2005. Results show that physicians ordered substantially more scans once they began billing for MRI. For example, after orthopedists began billing for MRI, the number of MRI procedures used within thirty days of a first visit increased by about 38 percent. Not only did MRI spending increase for their patients, but spending for other aspects of care rose as well. Attention should be paid to ensuring that advanced medical equipment acquired in physician practices is used appropriately.