In this study, an investigation is carried out to analyse the earthquake induced pounding be-tween two insufficiently separated base isolated buildings considering the inelastic behaviour of the struc-tures’ response. The buildings are modelled as a four-story and a three-story system to simulate the structural behaviour. The resulting systems of second order constant coefficient equations are reformulated as a system of first order ordinary differential equations and solved using the ordinary differential equation solver of MATLAB. Numerical study revealed that pounding behaviour of the buildings has considerable influence on the behaviour of the lighter building causing substantial amplification of the response and leading to consider-able permanent deformations due to yield. The parametric investigation has led to the conclusion that the peak displacement of the lighter and more flexible building is very sensitive to the structural parameters by varying gap size, story mass, the friction coefficient for sliding, and structural stiffness, whereas the effect of the heav-ier base isolated building was negligible.