In this paper, attention is focused on the modelling ofthe seismic response of RC walls with different reinforcement ratios. A numerical investigation is carried out with reference to three different specimens, whose measured seismic responses were obtained by other authors. For each specimen, an interpretation of the experimental results is attempted through a finite element non-linear cyclic model. A concrete model including a smeared cracking capability is used, which allows the sequence of crack opening and propagation through the shear wall specimens to be followed. Although the walls have the same geometry, their seismic behaviour and final failure mode are affected by the reinforcement ratio and detailing provisions. Some of the parameters and mechanisms which significantly influenced the specimens response are described. Knowledge gained from this study is important in understanding the behaviour of RC walls under earthquake loading and will help development of earthquake-resistant design.