Phyllodes tumors are unusual biphasic fibroepithelial neoplasms of the breast, accounting for < 1% of all breast tumors and raising issues of diagnosis and therapeutic choice. They can grow quickly and when the maximum diameter is greater than 10 cm. We talk about giant phyllodes tumors. Ultrasound, Mammography and FNA are not effective. A potentially useful diagnostic modality is MRI. Core tissue biopsy or incisional biopsy represent the preferred means of pre-operative diagnosis. Conservative treatment can be effective also in giant tumors depending upon the size of the tumor and the breast if a complete excision with an adequate margin of normal breast tissue can be achieved, so avoiding local recurrence often accompanied by worse histopathology. The Authors report the case of a giant benign phyllode tumor of the breast treated with conservative surgery, quadrantectomy and oncoplasty. No local recurrence at 4 years follow-up.