Architectural requirements many times lead to a structurally irregular building. One such irregularity of the geometry in elevation is called ‘step-back’. A step-back building is the one in which a portion of the building above a certain height is pushed-in towards the center or side. This leads to the change in both; mass distribution and stiffness distribution along the height of the building. The center of mass and the center of stiffness of different storeys do not lie along the same vertical line, resulting into predominant torsional modes of vibration during seismic events. The study of past earthquakes worldwide has revealed the poor performance of irregular buildings, which is detrimental to the structural safety and hence requires more comprehensive research. The paper presents study on seismic performance of five and ten storey RC frame buildings with different types of step-backs. The buildings are designed for elastic forces followed by pushover analysis and time history analysis using ETABS software. Further, the effect of step-backs on the dynamic characteristics, yield patterns, and storey drift is studied. The most appropriate step-back configurations from seismic considerations are suggested. This study will be of great help to architects and structural engineers, to select between the different step-back patterns and identify the possible regions within the structure that require special attention in designing and detailing.