Mounting malpractice liability costs might affect physician practice patterns in many ways, such as increasing the use of diagnostic procedures while reducing major surgeries. This paper quantifies the association between malpractice liability costs and the use of physician services in Medicare. We find that higher malpractice awards and premiums are associated with higher Medicare spending, especially for imaging services that are often believed to be driven by physicians’ fears of malpractice. The 60 percent increase in malpractice premiums between 2000 and 2003 is associated with an increase in total Medicare spending of more than $15 billion.