A beef production system was evaluated during a four year period in 39 hectares, utiiizing upgraded natural pastu res, formed by Agrostis tenuis, Holcus lanatus, Lolium perenne, Plantago lanceolata, and Hipochoeris radicata, among other species. Average stocking rate was 1.7 units/hectare and the pasture was utilized with rotational grazing during the whole year. Soil analysis was performed in order to determine the level of fertilization to be used each year; the average amount of fertilizers incorporated was: 23 u.N, 55 u.P2O5, and 25 u. K2O. Averages for the productive parameters were: parturition 91%, cow mortality 3.4%, calf mortality 8%, and replacements 25%. Weaning weights for females and males were 207.5 and 212.5 kg, respectively. The weight gain curve for growing animals showed the same shape than the seasonal forage production curve. At the peak, males gained 1.17 kg/day and females gained 1.11 kg/day, during November and December, each year. BulIs with 394 kg were slaughtered at 18 months of age, in March and April, each year. The system alIows to obtain about 350 kg of meat/hectare/year. This technology might be an alternative to increase the productivity of this large area in the IX Region of Chile.