Freshwater crabs are among the most threatened species, primarily due to their high levels of endemicity, poor dispersal ability, low fecundity and the relatively fragmented nature of freshwater ecosystems. Consequently, regional diversity of freshwater crabs can serve as surrogates for assessing the quality of aquatic habitats in the upper reaches of Baleh River in Sarawak. The six days of sampling during a scientific expedition in the area resulted in the collection of five species of freshwater crabs, including two notable discoveries. The freshwater crabs belong to the families Gecarcinucidae (Arachnothelphusa sp., Bakousa kenepai) and Potamidae (Ibanum aethes, Isolapotamon nimboni, one new genus). The formal description of the new genus and two new species will be made later in appropriate taxonomic journals. The new crab species tends to a specialist in habitat use, being found only from an unusual habitat - a sandy spring within undisturbed forests, near the Elite Honour Camp. These findings indicate that the undisturbed forest patches near the timber camp are important to support population of crabs.Keywords: Decapod crustacean, Gecarcinucidae, Potamidae, semi-terrestrial