An annotated catalogue of the horseshoe crabs (Chelicerata: Xiphosura) in the collections of the Museum fur Naturkunde Berlin is presented. The collection contains no type material, but representatives of all four currently recognised living species are present. These are Limulus polyphemus (Linnaeus, 1758) from the North American East coast, and Tachypleus gigas (Muller 1785), Tachypleus tridentatus (Leach, 1819) and Carcinoscorpius rotundicauda (Latreille, 1802) all from South-East Asia. Originally accessioned (in part) among the crustaceans, some material is related to the historically significant collectors Fedor Jagor, Hans Sauter and (probably) David Friedrich Weinland. The Berlin museum also hosts a number of high-quality historical anatomical preparations, some of which are also figured here for completeness (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)