Adnexal masses are rare in the young female population. The differential diagnosis includes ovarian masses, tubal/paratubal masses, masses related to the gastrointestinal tract (colon), infectious lesions, or pregnancy. Acute abdominal pain, and less commonly, precocious puberty or vaginal bleeding, are typical symptoms in these cases. The majority of adnexal masses in the paediatric and adolescent population are benign; however, a thorough preoperative assessment is essential to guide surgical intervention and optimise patient outcomes. The proper diagnosis of an adnexal mass, correct management (surgical or nonsurgical), and necessary referrals are of paramount importance. In the light of these cornerstones, this review describes the aetiologies, presenting symptoms, and appropriate diagnostic work-up for paediatric and adolescent patients affected by adnexal masses.