The first case of stromal sarcoma of breast occurring after augmentation mammaplasty is reported. The patient is 55-year-old Japanese woman who had received injection augmentation mammaplasty 19 years earlier. Both breasts indurated soon after mammaplasty and the patient felt a severe pain in her right breast for about 6 months before seeking treatment. Stromal sarcoma of the breast was proven by a subcutaneous mastectomy, and the determined histological subclassification was a malignant fibrous histiocytoma (MFH). The patient died with tumor recurrence 14 months after her first admission. The tumor cells were found to have invaded the surrounding tissue, such as the nerves, the muscle, the lymphatic vessels, and a severe reactive inflammation, caused by the injected material, was noticed.