SUMMARY: Benign fibrous histiocytoma of the knee is a very rare entity. We report on one case of benign fibrous histiocytoma that involved the patellar fat pad, an areas of involvement not previously reported. Diagnostic arthroscopy was performed to show retrobulging of infrapatellar fat pad without specific synovial changes. The lesion was completely resected. At short-term follow-up, all symptoms were resolved. Arthroscopy can be used as an diagnostic tool for identification of intraarticular lesions of the knee, but appears not to be a good tool for clean removal of mass within patellar fat pad.