The stromal ascorbate peroxidase of tobacco plants was crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol 4000 as a precipitant. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 37.2, b = 76.8, c = 98.8 A. The calculated V(M) value based on a monomer in the asymmetric unit is 2.2 A(3)Da(-1). A data set was successfully collected to 1.6 A resolution from a frozen crystal using synchrotron radiation of wavelength 1.0 A at KEK-PF, Japan.