We describe a patient who had nine primary malignant tumors and a germline mutation in the p53 tumor-suppressor gene, characteristically found in the Li-Fraumeni syndrome (LFS). A 15-year-old girl with no family history of cancer was referred to our hospital because of pain and swelling of the right knee. Osteosarcoma was diagnosed. The patient received chemotherapy followed by surgery and had a remission. After the age of 28 years, nine primary malignant tumors developed successively, including right breast cancer, colon cancer, malignant fibrous histiocytoma (MFH) of the abdominal wall, right lung double cancers, bilateral breast cancers, and MFH of the left thigh. This is the second highest number of types of primary malignant tumors to be reported in LFS. All tumors were treated by a multidisciplinary approach, including surgery. Genetic analysis revealed a germline missense mutation in the p53 gene (c.659 A > G), resulting in Y220C, which has been reported in three families with LFS. The patient died of lung metastasis from MFH at the age of 37 years. Despite the multiple tumors, repeated induction of remissions resulted in long survival. Our findings suggest that a multidisciplinary approach to treatment, including surgery, is beneficial in patients with LFS.