The flatworm (Phylum Platyhelminthes) collection of the Zoological Museum Amsterdam contains a broad spectrum of species and specimens from all over the world. However, the major focus of the collections concerns the triclad flatworms or planarians (Order Tricladida). From this group many species and specimens are available of marine, freshwater, as well as terrestrial planarians, including 385 type specimens. The beginning of these collections of planarians can be traced back to J. C. C. Loman (1856 - 1929), who described 16 new species of bipaliid land planarians. The collections were considerably expanded with the incorporation of the collection of Prof. Dr. Masaharu Kawakatsu into the collections of the Zoological Museum Amsterdam during the period 2000-2008.