The recrystallization behavior of a commercial AA3103 aluminium alloy, heat treated to various levels of Mn concentration in solid solution prior to cold rolling and recrystallization has been investigated. TTT-diagrams for the separate processes of decomposition of the supersaturated solid solution and recrystallization of the cold rolled matrix have been established. The TTT-diagrams show a strong effect of differences in Mn in solid solution before deformation and annealing. The precipitation noses are shifted to shorter times both by increased level of Mn in solid solution and increased strain. The recrystallizated grain size is strongly affected by concurrent precipitation during the recrystallization annealing. If precipitation occur prior to recrystallization, the grain structure becomes coarse and elongated in the rolling direction, but if the material recrystalizes prior to precipitation, a fine, equiaxed grain structure is obtained. On the basis of the observations, Grain-Size-diagrams have been constructed. These diagrams presents in a condensed form the various grain structures that will result upon recrystallization at various temperatures with different amounts of Mn in solid solution. Finally a diagram showing the critical heating rate to avoid concurrent precipitation, i.e. to achieve a fine-grained material after recrystallization anneal, has been constructed.