Juvenile giant fibroadenoma is a benign breast tumor and rare variant of the fibroadenomas. Clinical presentation is usually a painless, solitary and unilateral breast mass. It accounts for 0.5%-2% of all fibroadenomas and exact etiology is not known; however, hormonal influences are thought to be contributing factors. We present a case of a 20 cm diameter giant juvenile fibroadenoma of the breast in a 14-year-old girl. The patient was suffering from a painless, progressively enlarging mass for 1 year. Ultrasound revealed fibroadenoma and total surgical excision was performed. The patient is doing well in ten months of follow up.