The aim of this paper is to present a proposed methodology to select optimal scheduling rule for robotic fl exible assembly cells based fuzzy decision support system. Six common scheduling rules are considered, and three independent objectives, namely, the minimising of makespan (C max ), total tardiness (TD) and percentage of tardy jobs (%T) are measured. A fuzzy decision support system is implemented using the Matlab fuzzy toolbox. The fi nal results demonstrate the effectiveness of the proposed methodology to select optimal scheduling rule in a multi-product assembly environment.