The structural response of stainless steel I-sections in fire is investigated in this paper. Finite element models of stainless steel I-section members, capable of replicating their cross-section behaviour at elevated temperatures, are created and validated against existing experimental data from the literature. The validated finite element models are then utilised to perform comprehensive numerical parametric studies, where over 1000 numerical simulations of the response of stainless steel I-sections in fire are carried out, considering different cross-section dimensions, loading conditions, stainless steel grades and elevated temperature levels. On the basis of the findings from the parametric studies, the existing design rules of the European structural steel fire design standard EN 1993-1-2 and the recent design recommendations of Xing et al. [1], together with the plastic effective width method of Bambach and Rasmussen [2], are assessed in terms of their accuracy and reliability. It is observed that relative to the existing fire design rules set out in EN 1993-1-2, the design methods of Xing et al. [1] and Bambach and Rasmussen [2] are able to provide more accurate and reliable ultimate cross-section resistance predictions for stainless steel I-sections in fire, providing further verification of the suitability of the design provisions of Xing et al. [1] for inclusion in the next revision of EN 1993-1-2.