Paranasal sinuses are an infrequent site for tumor metastasis, and breast cancer metastasis to these sinuses is very rare. To date, less than 20 cases of breast cancer metastasis to paranasal sinuses have been reported. This case study’s purpose was to describe a 69-year-old woman with a history of breast cancer treated 15 years ago who developed the symptoms of rhinosinusitis. Physical examination showed exophthalmos and maxillary sinus tenderness. Finally, breast cancer metastasis to paranasal sinuses was diagnosed using CT scan. She received hormone therapy, systemic chemotherapy, and maxillary sinus radiotherapy. The treatment was well tolerated, and lesions observed in CT scan improved and after more than a year the patient is still alive.