The effect of copper content on dynamic grain growth in Al-Cu-Zr system was investigated by studying the microstructural development and texture evolution during uniaxial tensile deformation of Al-2wt%Cu-0.3wt.%Zr and Al-4wt%Cu-0.4wt.%Zr alloys at 450°C with a strain rate of 10-3s-1, with a similar initial microstructure in both materials. The initial microstructure consisted of layers of different orientations, the layers being separated by high-angle grain boundaries with low-angle boundaries separating grains within the layers. The initial grain spacing was about 5m and the texture was typical of rolled aluminium alloys. The 4wt.%Cu alloy gave a higher strain rate sensitivity index, m, and a greater ductility compared to the low copper content alloy. An increase in grain size occurred in both materials due to deformation, but this dynamic grain growth (DGG) was much greater in the material with the higher copper content. This was associated with a more rapid conversion of low-angle boundaries to high angle ones in the 4wt%Cu material which is consistent with changes in crystallographic texture occurring during deformation.