Phyllode tumors of the breast are fibroepithelial tumors similar to fibroadenomas but with a predominant conjunctive tissue component. They are rare with an incidence of less than 1% of all breast neoplasms. They can be divided in three categories: benign, borderline, malignant. The Authors report the case of a 53 years old woman who presented an exceptional 6.5 kg phyllod tumor od the left mamma. The diagnostic stategies, the surgical total mastectomy procedure with anterior thoracic parietectomy and the surgical reconstructive treatment are described.