Phyllodes tumors account for less than 1% of breast tumors in women. Giant phyllodes tumors are larger than 10 cm in diameter. A 40-year-old lady presented with a left breast lump that was present for two years. She underwent a simple mastectomy. The tumor was 30×26×21 cm in size, weighed 15 kg and had a density of 0.915 gr/cm3. We believe this patient had the third largest breast phyllodes tumor according to size, the second largest according to weight and had the highest density among all cases thus reported in English-language publications.