<p>This paper investigates on seismic responses due to interaction of mass irregular floors existed at different floor heights of a 10-storey building frame by performing nonlinear response history analysis (NRHA). For clarity in presenting results, only alternate floors are considered as mass irregular floors while performing interaction study. Further, differences on seismic responses between distribution of mass irregular intensity to different floor levels and concentration of the equivalent mass irregular intensity to a single floor level is also investigated. Force analogy method (FAM) is used for performing NRHA. 150% mass irregularity is used for interaction study whereas for comparative study 150% and 300% mass irregularities are used. The analysis results are presented as storey drift, dissipation of inelastic energy and intensity of input ground motion amplitudes. Upon investigation, it has been observed that degree of mass irregular frames to become unstable state, i.e., degree of instability, increases as the position of mass irregular floors approaches each other along the building height and vice-versa. It has also been observed that the degree of instability of mass irregular frames increases as the closely placed two or more mass irregular floors move downward along the building height and vice-versa. Further, it has also been found that seismic responses of mass irregular building frame become favourable when mass irregular intensity is distributed to different consecutive floor levels rather than concentration on a single floor level along the building height.</p>