The purpose of this article is to review the MRI characteristics of musculoskeletal tumors, including skeletal and soft tissue masses. MRI has become the premier imaging modality for the evaluation of musculoskeletal tumors because of its excellent soft tissue contrast, its sensitivity to bone marrow and soft tissue edema, and its multiple imaging planes. In a substantial subset of cases, MRI can provide a diagnosis or a short differential diagnosis, while certain tumors have no distinguishing signal characteristics. MRI of musculoskeletal tumors can also be challenging, because the MRI appearance of certain lesions can be misleading, and a knowledge of the instances in which MRI over- and underestimates the malignancy of lesions is invaluable. The importance of correct protocols for tumor evaluation, both in diagnosis and in pre-operative evaluation, are discussed. Common pitfalls that may over- or underestimate the aggresivity of lesions will be highlighted, as will the role of gadolinium enhancement in the evaluation of lesions. The MRI appearance of common benign and malignant muculoskeletal lesions will be illustrated.