The Windbreak plantations contribute to the agricultural development in south Patagonia. Predicting the growth and windbreak dynamic allow us to cuantify the protected agricultural area and the wood volume to be harvested. The aim of this work was to develop biometric models for Populus nigra cv ‘Italica’ in different sites, crown classes and inter-tree distances for Santa Cruz windbreaks. A modification of Chapman-Richards model was used to fit the diametric and heigth growth equations. Schumacher-Hall model was used to predict the volume, while multiple regression technics defined the crown dynamics models. The ajusted models have good statistics and biological significance. The multiple factors that affected the windbreaks growth could be explained by easy measured variables (DBH, total heigth, crown classes, site).