Location, location, location: All the stereoisomers of 5‐OP‐RU were synthesized to elucidate the effects of its stereochemistry on MR1‐dependent MAIT cell activation. Of the stereoisomers, only the 4’‐OH epimer demonstrated potent MAIT cell activity, thus indicating that the configuration of the 2’‐OH and 3’‐OH group could be important for agonistic activity.