The combined effects of climate changes and increases in atmospheric CO2 concentration on the potential growth of three grapevine varieties (Cabernet Sauvignon, Pinot noir and Chenin blanc) are studied using the crop growth model proposed by Gutierrez et al., 1985. For the simulation of future grapevine potential growth current climatic conditions are adjusted according to the changes predicted by General Circulation Models (GCMs), and model assimilation and growth parameters are modified for adapting the model to increased atmospheric CO2 concentration. The results of the study indicate that the combined action of climate changes and increasing atmospheric CO2 concentration might cause a general increase in fruit and total vine dry mass. The amount of these increases, however, depends both on the varieties and the GCM climate change scenario used.