Gynecologic sonography has matured into a highly effective and accurate tool enabling confident diagnosis of a variety of adnexal masses. Using a practical evidence-based approach, sonologists are well equipped to differentiate expected findings in the normal ovary from pathologic entities and can often generate specific conclusions regarding the cause of an adnexal mass. Mastery of the diagnostic strategies to use when an adnexal mass is identified and the sonographic patterns of various types of adnexal pathology contributes greatly to the proper and cost-effective care of a woman with an adnexal mass.