From 2006 to 2008, surveys on the medical arthropods were conducted In the Cuc Phuong, Ba Be, Tam Dao National Parks and io a Nature Reserve, Can Gio mangrove forest. A total of 13778 individuals of the medical arthropods and 254 species have been collected, including 4 species of flea (Siphonaptera), 11 species of tick (Ixodidae), 25 species of chiggs (Trombiculidae), 29 species of mites (Gamasoidea), 88 species of mosquitoes (Culicidae) and 97 species of flies (Brachycera). They belong to 81 genera, 16 families, 3 orders (Siphonaptera, Acarina and Diptera), and 2 classes (Insecta and Arachnida). 32 species of epidemiological significance were found in almost all sites surveyed. In comparison with the whole country, the species diversity of the medical arthropods in the three NPs and Can Gio NR was at the rate of 30.2 percent. The medical arthropods were the most abundant in Cuc Phuong NP.