We have established reference intervals for healthy adults of serum thyrotropin, free thyroxine and free triiodothyronine using the AutoDELFIA (Wallac, Finland) automatic measuring device. The determination of reference intervals in a proper manner is costly, and many laboratories adopt reference ranges from the literature rather than determining them alone. This is the first report on reference values in thyroidology where this automatic system based on time-resolved fluorescence has been used. The reference intervals for thyrotropin, free thyroxine and free triiodothyronine were 0.6-4.3 mIU/l, 9.6-17.1 pmol/l and 4.3-7.5 pmol/l, respectively.