Background: Pseudoangiomatous stromal hyperplasia (PASH) is a rare benign breast lesion that is is extremely rare in children and adolescents. Case: A 13-year-old girl was admitted to our clinic with a giant mass in the left breast for 3 months. Physical examination findings of the patient were normal except for the mass in the breast. The mass was removed totally, and its pathological diagnosis was pseudoangiomatous stromal hyperplasia. The patient has been followed up for 6 months without disease.