For this study, Red junglefowl were raised in Cuc Phuong National Park. The subjects consisted of 372 chickens which were monitored for biological and growth characteristics from birth to 20 weeks of age. The results showed that the body externality of the chickens: the horny was gray, leg leather was lead and chick at birth had yellowish-brown color running along the body. At 20 weeks, the males were red flags and females were almost solid. Their eating, sleeping and sex habits were similar to those of local chickens, but eggs were laid in the spring which chickens started laying eggs in the spring and ended in early autumn. The rate of growth was slow. Body weight at birth was 22.2 g, and at 20 weeks roosters and hen weighed 642.7 g and 1136.7 g. The feed conversion ratio was 4.10 and 5.84, respectively. The survival rate was high: 81.45 percent (to 20 weeks). The jungle chickens adapted well to living conditions in Cuc Phuong National Park.