Aim: To present a case of a very rare huge aggressive extraabdominal fibromatosis of the abdominal wall, which appeared after adjuvant radiotherapeutic treatment of prostatic cancer at the place of the postoperative scar in a 70-year-old patient, describe the diagnostic pathway, treatment and final outcomes. Case report: A 70-year-old male presented with palpabile anterior abdominal wall tumor mass. Clinical examination revealed firm and painless, 9 cm tumor mass of the right inguinal and suprapubic region, which was fixed and appeared infiltrative. Preoperative pathohistology analysis of tumor biopsy referred to aggressive extraabdominal fibromatosis. An abdominal computed tomography scan showed that the mass belonged to the abdominal wall without intraabdominal propagation. Magnetic resonance was performed in order to see the relationship between the tumor and the soft tissue. The tumor assessed as operabile. During the operation the muscles were perserved but the aponeurosis of external abdominal oblique muscle was removed along with the tumor. The resultant defect of aponeurosis was reconstructed with a prolene mesh which was fixed in the defect of the aponeurosis of external abdominal oblique muscle in order to prevent postoperative muscle hernia. The rectus abdominis muscle was covered with the seams of the anterior leaf of its sheath. The defect was primary reconstructed without significant tissue tension. The tumor was extirpated radically and sent to PH examination that revealed the extraabdominal aggressive fibromatosis with 1 cm of free margins. The postoperative course was uncomplicated. Conclusion: Extraabdominal fibromatosis of the abdominal wall is a sporadic tumor. Pathohistological examination, imaging and physical examination are essential diagnostic methods. The radical extirpation is essential for treatment. Our patient is without signs of recidive for a follow up of two years after surgery.