Masonry is not a simple material, the influence of mortar joints as a plane of weakness is a significant feature and this makes the numerical modelling of masonry very difficult especially when dynamic (seismic) analysis is involved. In order to develop a simple numerical model for masonry under earthquake load, an analytical model based on Distinct Element Method (DEM) is being developed. At the first stage, the model is applied to simulate the in-plane shear behaviour of an unreinforced masonry wall with and without opening where the testing results are available for comparison. In DEM, a solid is represented as an assembly of discrete blocks. Joints are modelled as interface between distinct bodies. It is a dynamic process and specially designed to model the behaviour of discontinuities. The numerical solutions obtained from the distinct element analysis are validated by comparing the results with those obtained from existing experiments and finite element modelling.