Introduction: Isla del Coco National Park is an oceanic island of great interest and scientific value; however, little is known about its entomological fauna, particularly for the Order Diptera. Objective: To present the diversity of “flies” housed in the collection of arthropods of the National Museum of Costa Rica (MNCR), from expeditions made to the island between 1994 and 2013. Methods: Analyzed the 2 129 physical and digital records from Specify and other data bases, as well as the literature. Results: A total of 30 families, 43 genera and 28 species are represented in the MNCR, from a taxonomic determination work carried out by a group of more than 30 experts. There is material both in the Diptera collection of the MNCR and the MZUCR (Museum of Zoology, University of Costa Rica), as well as in institutions outside the country. Conclusion: The sampling effort has been concentrated in only one sector of the island; therefore, diversity is expected to be greater. It is essential to maintain research taxonomic efforts of the entomological fauna to expand the knowledge of the diversity present in such a valuable resource, Heritage of Humanity: Isla del Coco.

Keywords: Cocos Island; Isla del Coco; oceanic island; entomofauna; insects; Diptera taxonomy; arthropods.