Positron annihilation lifetime is one of the most important nuclear techniques, used to study the isochronal and isothermal annealing in aircraft (7075) alloy. Samples of 25 % deformation have been used for these studies. One recovery stage during the isochronal annealing [1] was observed which attributed to recovery of dislocations induced by the deformation. The isothermal annealing measurements were performed at 643, 663, 683 and 703 K from which the activation energy is obtained as 1.35 +/- 0.16 eV.