Osteolysis around total knee arthroplasty (TKA) can be difficult to identify and quantitate on plain radiographs. This study reports on magnetic resonance imaging (MRI) with metal suppression for the evaluation of suspected periprosthetic osteolysis around TKA. We retrospectively reviewed 11 patients referred for MRI with suspected periprosthetic osteolysis. Radiographic and MRI findings and findings at revision arthroplasty were correlated. The presence of osteolysis was identified or suspected radiographically in all of the 11 patients. Osteolysis was confirmed in 10 patients by MRI. In 9 of 11 patients, the extent of osteolysis was greater on MRI than estimated radiographically. In 5 of 11 patients, MRI demonstrated additional osteolytic lesions which were radiographically occult. In one case, the amount of osteolysis on MRI was less than on initial radiographs, and in one case, osteolysis was felt to be present radiographically but was not confirmed on MRI. In all 7 of 11 patients subsequently treated with revision TKA, MRI findings were confirmed at revision.