During the 2004 2005 and 2006 growing seasons physiological and anatomical leaf characteristics and productivity were studied in field-grown grapevines (Vitis vinifera L.) cv. \Touriga Franca\ under ambient (C 365 ± 10 ppm) or elevated carbon dioxide [CO2] (E 500 ± 16 ppm) under Open-top chambers (OTC-C and OTC-E respectively). The elevated [CO2] concentra- tion increased net photosynthetic rate (A) intrinsic wa- ter use efficiency (A/gs) leaf thickness Mg concentra- tion C/N K/N and Mg/N ratios and decreased stomatal density and N concentration. Nevertheless stomatal conductance (gs) transpiration rate (E) photochemi- cal efficiency (Fv/Fm) leaf water potential SPAD-values and Red/Far-red ratio transmitted by leaves were not significantly affected by [CO2]. Meanwhile there is no evidence for downward acclimation of photosynthesis and stomatal conductance. Yield cluster weight and vigour showed an increase in elevated [CO2] treatment but yield to pruning mass ratio was unaffected. Despite elevated [CO2] stimulates grapevine photosynthesis and yield more long-term studies particularly at sub-opti- mal nutrient and water availability are needed in order to reveal the grapevine responses to climate change in the Mediterranean area.