7075-T6 alloys have high mechanical and limited formability properties at room temperature. In aluminium alloys, the applied annealing process before the forming operation improve formability but also affect the mechanical and microstructural properties of the alloy. In order to determine these effects, the effects of annealing parameters on the mechanical and microstructural properties of 7075-T6 sheet material were investigated experimentally. Annealing temperature (100, 200, 300 and 400 degrees C) and annealing time (6, 30 and 60 min.) were determined as experimental study parameters. Tensile and hardness measurement tests were used to observe the variation in mechanical properties of the alloy. It was observed that the annealing process reduces the mechanical properties of the 7075-T6 material. In experimental study, it was determined that while annealing parameters changed from 20 degrees C to 100 degrees C-60 min. mechanical properties of sheet were not changed. Also, it was determined that the mechanical properties of sheet started to decrease after the 200 degrees C-6 min. annealing parameter and this decrease was significantly increased after 200 degrees C-60 min. annealing parameter. It was observed that the mechanical properties of the material at 20 degrees C were decreased by 68,85% as a result of the annealing process at 400 degrees C. It was determined that, this situation comes from due to precipitation formation and material grain size increase after the 200 degrees C annealing temperature and 60 min. annealing time.