Background Inappropriate MRI use has been targeted as a particular area of concern in orthopaedics, but it is unclear whether and to what extent its use is inappropriate in musculoskeletal oncology. Questions/Purposes We therefore evaluated the incidence and cost of inappropriate prereferral MRI among patients with musculoskeletal tumors. Methods We retrospectively identified 920 patients treated in a musculoskeletal oncology clinic between 2009 and 2010. We accepted as necessary any MRI for a primary bone sarcoma, for biopsy-proven soft tissue sarcomas, for soft tissue masses greater than 5 cm in diameter, for soft tissue masses deep to the fascia, for painful soft tissue masses, and for growing soft tissue masses. Patients without these criteria were reviewed by a team of musculoskeletal oncologists to determine the necessity. The criteria for a repeat MRI were failure to show the tumor, lack of gadolinium contrast, lack of T1 or T2 MRI sequence, or poor image quality. Cost was determined using 2010 Medicare reimbursement rates. Results Of 920 patients, 320 (35%) arrived with a prereferral MRI study. Eight of the 320 (3%) studies were unnecessary, and 12 (4%) were necessary but were repeated. The cost was $11,474, which averages to $574 per study and $36 of waste per patient referred with an MRI study. Conclusions Based on our data, we judged MRI use before referral to our tertiary center as not excessive. This is likely attributable, in part, to the relatively low use of MRI in our referral base. Inappropriate MRI use in patients with tumors may not be as widespread as previously reported.