The retroperitoneal localization of a schwannoma or neurilemmoma undoubtedly represents an unusual occurrence (0.5-0.7% of all sites); this data, together with the absence of a typical clinical picture and the lack of peculiar instrumental signs, make a preoperative diagnosis of this lesion really hard to ascertain. In this paper, on the basis of a case report successfully treated, the Authors review the literature analysing current diagnostic and therapeutic work up, mainly emphasizing controversies in determining a proper preoperative diagnosis among all retroperitoneal tumours.