The caspase-recruitment domain (CARD) is known to play an important role in apoptosis and inflammation as an essential protein-protein interaction domain. The CARD of the cytosolic pathogen receptor Nod1 was overexpressed in Escherichia coli and purified by affinity chromatography and gel filtration. The purified CARD was crystallized at 277 K using the microseeding method. X-ray diffraction data were collected to 1.9 A resolution. The crystals belong to space group P3(1) or P3(2), with unit-cell parameters a = b = 79.1, c = 80.9 A. Preliminary analysis indicates that there is one dimeric CARD molecule in the asymmetric unit.