This paper describes data collected about consistence, density and social structure of Sardinian deer (Cervus elaphus corsicanus Erxleben, 1777) subspecies of European deer (Cervus elaphus Linnaeus, 1758) from 1989 to 2004. The study area is located in the WWF Faunal Park of Monte Arcosu (south-western of Sardinia). The flora of the Reserve is typical Mediterranean vegetation. The data have been collected with two different methods, using both roaring census and direct observations. Results show a population growth of 78.8%, during the study period. The sex ratio was 1:1.9. The social structure observed show that adult male were the 20.04% of population, young male the 9.17%, female the 52.31% and the young 18.49%. The number of deer for adult male varied between 3.63 and 4.53. In the 2004 density was 28.6 deer/km2, 1028 deer were value in the Reserve.