The emergence of different fabrication techniques of silicon nanowires (SiNWs) raises the question of finding a suitable architectural organization of circuits based on them. Despite the possibility of building conventional CMOS circuits with SiNWs, the ability to arrange them into regular arrays, called crossbars, offers the opportunity to achieve higher integration densities. In such arrays, molecular switches or phase-change materials are grafted at the crosspoints, i.e., the crossing nanowires, in order to perform computation or storage. Given the fact that the technology is not mature, a hybridization of CMOS circuits with nanowire arrays seems to be the most promising approach. This chapter addresses the impact of variability on the nanowires in circuit designs based on the hybrid CMOS-SiNW crossbar approach.