An ovarian teratoma, (dermoid cyst) is a germ-cell tumor that contains a diversity of tissues including hair, teeth, bone, and neural tissue. Ovarian teratomas are best evaluated with a combination of transabdominal and transvaginal ultrasound. Teratomas range in size and echogenicity and often have a mixture of different sonographic patterns reflecting their contents. The two classic dermoid appearances are the “tip of the iceberg” sign and the “dermoid plug” sign. The “tip of the iceberg” sign is characterized by a sonographic pelvic mass in which most of the sonographic beam is absorbed at the top of the mass preventing visualization of the contents of the mass. The “dermoid plug” sign is characterized by one or more hyperechoic rounded areas within the mass. These “dermoid plugs” represent solid tissue components (teeth, hair, bone) surrounded by sebaceous material. On CT, teratomas are seen as a pelvic mass with mixed contents reflecting various elements such as sebum, skin, hair, and teeth.