Abstract | During the last decade, significant progress has been made toward the development of probabilistic methods for the seismic assessment of structures. However, the use of existing analytical fragility methodologies for practical applications related to structures of moderate to low importance remains prohibitive, in part due to substantial computational demands. This paper explores, through a case study, the robustness of a simplified methodology for fragility assessment of regular steel Moment Resisting Frames (MRFs). Through comparisons with a more accurate but computationally demanding methodology, it was confirmed that the “2000 SAC/FEMA” procedure gives robust fragility estimates. Moreover, it was found that a closed-form fragility assessment, where the structural response is evaluated by means of an Equivalent Single Degree Of Freedom (ESDOF) oscillator, can yield sufficiently accurate results for regular steel MRF structures, providing acceptable construction quality has been achieved in the connections.