Research into the biomechanical properties of tendons had led to a better understanding of the functional and pathophysiologic processes that occur in vivo, particularly in the setting of tendon injury and failure. Increasingly, biomechanical information is being utilized in the clinical setting, guiding patient management in certain circumstances. Differentiating minor and self-limiting abnormalities from those in which specific treatment may prevent further disability from altered biomechanics may become an important role for imaging. This article examines normal tendon anatomy and its relationship to tendon biomechanics under both physiological and pathologic conditions. Imaging characteristics of tendons in the physiologic and pathologic states are discussed. We have focused primarily on MRI, as this modality has been studied most intensively and has been shown to offer additional information regarding unsuspected pathology.