Abstarct: Recent Iranian earthquake damages like the damages caused by the Kermanshah earthquake, revealed that RC buildings having soft story irregularities experienced more seismic vulnerability. Moreover, earthquake aftershocks increased the seismic failures in past earthquake events. But they are not included in recent seismic design codes. In this article, for assessing the effects of soft story irregularities and also the earthquake aftershocks, 3,5 and 8 story RC models having intermediate sway frxames are designed and then modeled in OPENSEES and then IDA analysis are performed in order to producing the seismic fragility curves consistent with HAZUS definitions. The resulting seismic fragility curves revealed the influence of soft story irregularities and also main shock-aftershock sequences on the vulnerability of considered RC models. By increasing the height of the RC structures, the effects of soft story irregularities and the aftershocks decreased in seismic vulnerability of the considered buildings.