Understanding subterranean biodiversity is important, yet vast regions of the world remain poorly explored. Here, we provide the first step towards cataloguing the subterranean arthropods of Iran. After review and analysis of the available literature and the examination of samples collected by us from Iranian caves, we listed 89 cavernicolous species (from 42 caves and 5 karstic springs) belonging to four arthropod subphyla: Chelicerata (1 class, 4 orders, 36 species), Crustacea (2 classes, 3 orders, 15 species), Hexapoda (2 classes, 5 orders, 34 species) and Myriapoda (2 classes, 3 orders, 4 species).