Recent studies demonstrated successful forming of AA7075-T6 sheet at 200 °C into a complex component with no visible defects. This process is termed retrogressionRetrogression forming. The potential for springback during retrogressionRetrogression forming depends strongly on stress relaxationStress relaxation, for which no previous data exist. Stress relaxationStress relaxation was measured at 200 °C in AA7075-T6 sheet following tensile deformation at two different strain rates, 3.2 × 10–2 and 3.2 × 10–3 s−1, to two different true strains, 0.05 and 0.10. Stress relaxed by as much as 45% while specimens were held at a constant strain following tensile deformation. Most stress relaxationStress relaxation occurred within the first 60 s after straining. The fastest strain rate produced the largest flow stress but, unexpectedly, also produced the lowest stress after relaxation. Strain in the range of 0.05–0.10 did not present a significant effect. Stress relaxationStress relaxation measurementsMeasurements and the mechanistic sources of stress relaxationStress relaxation will be discussed.