Imaging plays a central role in the diagnosis of adnexal masses, from the initial detection to characterization. Although ultrasound is often the first-line imaging modality in patients with adnexal masses, magnetic resonance imaging, computed tomography, and sometimes positron emission tomography-computed tomography are used for further evaluation. This chapter discusses the role of different imaging modalities in the evaluation of adnexal lesions as well as provides a summary of key imaging findings of common adnexal lesions.