In this paper, tension compression tests are carried out on AA6111 specimens in order to characterize the internal stress. The impact of the microstructure is investigated by applying a variety of ageing conditions to the specimens prior testing. It is shown that the Bauschinger effect depends strongly on the precipitation state. More precisely, when the precipitates are still shearable by the dislocations, no significant internal stress is found, although when the precipitates are large enough, a large internal stress, up to 30% of the yield stress, is observed.