In this study, the effect of different doses of gamma-irradiation (0, 1, 5 and 10 kGy) on colour, antioxidant activity and phenolic compounds of shade-and freeze-dried samples of Tuberaria lignosa were evaluated and compared. The last two parameters were performed on decoctions and infusions in order to investigate the influence of the preparation method as well. In general, gamma-irradiation has no influence on colour parameter; changes caused by this technology were only identifiable on the lipid peroxidation inhibition capacity of the shade-dried samples and also on a few phenolic compounds. Differences among preparation method were significant for all assayed parameters, being decoctions preferable over infusions, as indicated by the higher antioxidant activity and levels of phenolic compounds. Overall, the gamma-irradiation treatment (up to 10 kGy) did not significantly affect the analyzed parameters. Nevertheless, other studies are of interest to evaluate the preservation effectiveness of this technology.