Crystal and molecular structure of the compound 4-n-ethyl-4′-cyanobiphenyl (2CB), which exhibits nematic phase monotropically, is determined by direct methods from single crystal X-ray diffraction data. The crystal belongs to monoclinic system with space group P21, cell parameters beinga= 8.584(4),b= 5.865(3),c= 11.833(3) (Å) and β = 92.30(3)° with 2 molecules per unit cell. Refinement led toR= 0.079 withI> 2[sgrave](I). The molecules are in the most extended conformation. The phenyl rings are highly planar, the dihedral angle between them is 1.46°. Antiparallel pairs of 21symmetry related molecules are arranged in layers and the layers are stacked along [001]. The thickness of these layers is equal to the length of crystallographicc-axis. van der Waals' type of contact encompasses all the molecules within a layer. Molecular geometry and crystal packing are discussed in the context of geometry and packing of other knownnCB andnOCB structures.