Peroxiredoxins (Prxs) make up a family of antioxidant enzymes that decompose hydroperoxides with the expense of a thiol-containing reducing agent. Alkyl hydroperoxide reductase (Ahp1p) from Saccharomyces cerevisiae is a member of Class 3 Prxs that is highly expressed in response to hydroperoxide insult. It presents a higher catalytic efficiency towards organic hydroperoxides and is believed to function as an important defense in stationary-phased and aerobic-grown yeast cells. Recombinant Ahp1p was expressed in Escherichia coli as a His6-tagged fusion protein and was purified by nickel-affinity chromatography. The protein was crystallized using the hanging drop vapor diffusion method after treatment with tert-butyl hydroperoxide in the presence of PEG 3000 as precipitant. X-ray diffraction data were collected to a maximum resolution of 2.2Ǻ at the protein crystallography beamline D03-MX1 of the Brazilian Synchrotron Light Laboratory. Crystals belong to the space group P2₁ with unit cell parameters a=39.12, b=127.79, c=66.42Ǻ, b=103.23°. Crystal structure was solved by molecular replacement methods using the program Phaser and atomic coordinates from human PrxV as the search model. Structure refinement is currently in progress.