An open top chamber (OTC) study has been conducted during the growing seasons of 2010 and 2011 over a vineyard located in Angera, northern Italy. Four OTCs were used. Two of them were fumigated with air from which ozone had been partly eliminated, and two others were fumigated with ambient air. Ozone concentration was monitored in both filtered and non-filtered chambers, as well as in outside air. At harvest time, grapevine bunches grown inside and outside the OTCs were cut and investigated for various ponderal and chemical parameters. Results were compared with ozone exposure (AOT40) and phytotoxic ozone dose (POD) as calculated by the DO3SE model. Grapes exposed to enhanced ozone doses or concentrations showed sensitivity towards weight per bunch, degree Brix (related to sugar content), malic acid and polyphenol concentrations. Ozone thus seems to affect both yield (volume of wine production) and quality of the final product.