SARS coronavirus (SARS-CoV) is the aetiological agent of the highly infectious severe acute respiratory syndrome (SARS). To gain a better understanding of SARS-CoV replication and transcription proteins, a preliminary X-ray crystallo-graphic study of the C-terminal domain of SARS-CoV nonstructural protein 2 (nsp2) is reported here. The C - terminal domain of SARS-CoV nsp2 was cloned, overexpressed, purified and crystallized using polyethylene glycol 5000 monomethyl ether as the precipitant; the crystals diffracted to 2.5 ร… resolution. The crystals belonged to space group P6 5, with unit-cell parameters a = b = 112.8, c = 91.1 ร…, ฮฑ = ฮฒ = 90, ฮณ = 120ยฐ. One molecule is assumed to be present per asymmetric unit, which gives a Matthews coefficient of 2.89 ร… 3 Da -1 and a solvent content of 56.2%. ยฉ 2011 International Union of Crystallography