Background: Aggressive fibromatosis, also known as desmoid tumors, are histologically benign fibrous neoplasms arising from the musculoaponeurotic structures throughout the body. Aggressive fibromatosis has the tendency to locally invade and erode adjacent vital structures while it never metastasises.

Case Report: Here, we report a case of a patient with aggressive fibromatosis in the left side of neck. While the tumor deeply invaded to the scalene muscles, the lesion was succssfully treated by surgery followed by radiotherapy. The patient has been alive without disease for 7 years after the treatment.

Conclusion: Due to its rarity in the head and neck region, we should keep aggressive fibromatosis in mind as a differential diagnosis of the invading lesion in the neck. Clinical course was reported with review of the literature.