The slow loris (Nycticebus) is a prosimian that is popular among exotic pet lovers. In Japan, many slow lorises have been imported illegally. Prosimians that have been confiscated in raids are protected in Japanese zoos, and the number of such animals has increased. In most cases, the country of origin remains unknown and even the species can be difficult to identify from the animal’s physical appearance alone. We have attempted to resolve this problem by using DNA analysis. DNA samples of five species, consisting of the Pygmy slow loris (Nycticebus pygmaeus), Bengal slow loris (Nycticebus bengalensis), Sunda slow loris (Nycticebus coucang), Javan slow loris (Nycticebus javanicus), and Bornean slow loris (Nycticebus menagensis), were extracted, amplified, and the nucleotide sequences of mitochondrial 12S rRNA, 16S rRNA, and the cytochrome oxidase subunit 1(COI) regions were compared. Differences of nucleic acid sequences of representative individuals were demonstrated.