This study investigated the interacting effects of carbon dioxide and ozone concentrations on the growth and yield of spring whet (Triticum aestivum L. cv. Wembley). Plants were exposed from time of sowing to harvest to reciprocal combinations of two carbon dioxide and two ozone treatments: [CO2] at 350 or 700 μmol mol−1, and [O3] at < 5 or 60 nmol mol−1. Records of leaf emergence, leaf duration and tillering were taken throughout leaf development. At harvest, biomass, yield and partitioning were analysed. Our data showed that elevated [CO2] fully protected against the detrimental effect of elevated [O3] on biomass, but not yield.