Background: Abnormalities of the ovary are frequently seen on ultrasound examination, sometimes symptomatic, but are more commonly asymptomatic. Purpose: Presentation of the most important entities of ovarian masses and their imaging features in infants and children. Discussion of criteria for differentiation between benign and potentially malignant masses. Materials and methods: Review of current literature and presentation of image examples. Results: The most common lesions are ovarian cysts in infants, which usually do not require therapy. Because of the risk of torsion, surgery should be discussed for lesions with a size of 5 cm or more. Benign teratomas represent three-quarters of all solid tumors of the infantile ovary. Malignant masses are rare. The task of imaging is to assess the potential risk of malignancy, also using imaging scores. Conclusions: Imaging plays a crucial role for therapeutic considerations. Depending on the potential risk, ovarian-sparing surgery is preferred to preserve fertility, as long as the oncologic risk is reasonable.