A retractor with at least two spreader arms that can be displaced relative to one another and can be blocked by a blocking device and on their end sections are provided with blades that can be displaced in their gripping ranges. The blades are of unit construction and are inserted so that they can slide in linear guides forms from spreader arms in such a manner that can be fixed in a range of freely chosen positions each corresponding to various griping ranges by means of a releasable fixing device.