Tanzania is internationally recognised as a key country for the conservation of African biological diversity. Its herpetofauna numbers about 130 amphibians and over 275 reptiles, many of them strictly endemic and included in the “IUCN” Red lists of different countries. This unique resource is still relatively unknown even if amphibians and reptiles are ideal subjects for zoological inventories and biogeographical analysis as they are relatively easy to survey and often strictly related to a particular environment. Moreover, since 1989 the scientific community has started to realise that amphibians are declining in many areas of the world and that they are more sensitive than other species to diverse environmental modifications. This is probably due to the fact that their larval and adult stages occupy different habitats and have limited vagility (Stebbins & Cohen, 1995; Houlahan et al., 2000). Despite its importance, the Arusha National Park herpetofauna has never been completely studied up to now, even if some scientific papers showed already its peculiarity and importance. The aim of this booklet is to fill the existing gap in the literature and to provide a stimulus that will strengthen ecological tourism in the park. Visitors will be encouraged to appreciate also this fascinating and a bit mysterious component of the ecosystems.