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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] concentration increased net photosynthetic rate (A), intrinsic water use efficiency (A/g_s), leaf thickness, Mg concentration, C/N, K/N and Mg/N ratios and decreased stomatal density and N concentration. Nevertheless, stomatal conductance (g_s), transpiration rate (E), photochemical efficiency (F_v/F_m), leaf water potential, SPAD-values and Red/Far-red ratio transmitted by leaves were not significantly affected by [C0₂]. Meanwhile, there is no evidence for downward acclimation of photosynthesis and stomatal conductance. Yield, cluster weight and vigour showed an increase in elevated [C0₂] treatment but yield to pruning mass ratio was unaffected. Despite elevated [C0₂] stimulates grapevine photosynthesis and yield, more long-term studies, particularly at sub-optimal nutrient and water availability, are needed in order to reveal the grapevine responses to climate change in the Mediterranean area.