Simultaneous measurement of tritium in urine and saliva in exposed workers reveals differences in the kinetic fate of this radioelement in these two bodily fluids. During two years, four cases of accidental exposure, affecting seven workers, were used for these bioassays. Since the concentration of tritium increases much faster in saliva than in urine, a ratio estimated at 1 to 30 at about 30 minutes after contamination occurs, it is possible to consider saliva assay as an alternative to urine assay, which is more common practice today.