I. A n anaiysis of the findings in a series of 25 cases of giant fibro-adenoma of the breast in adolescent females is presented together with a review of the relevant literature. The clinical features, histology, prognosis and treatment of these tumours are discussed.2. Follow-up ofjrom 2 to 8 years after total excision of the tumours has shown that normal breast development occurred in all the cases. There was no recurrence or distant metastasis.3. Despite clinicaljeatures and histological characteristics suggestive of malignancy the tumour has been found in our experience to be strictly benign inpatients under the age of 20 years.