Serum transferrin saturation (TS) values were calculated on the basis of serum iron and transferrin (protein) measurements in a total of 2425 serum samples from six groups of subjects: individuals applying for selection as blood donors (M and F, median age 34 and 32 years); patients referring to the hospital laboratory for routine testing (M and F, median age 45 and 48 years); and elderly subjects living in a specialized institute (M and F, median age 76 and 82 years). In the first four groups the frequency of TS values <15% and >62% respectively, was substantially as expected, considering the average health conditions and sex. These results indirectly support the reliability of the measurement procedure. In the elderly group, however, the frequency of TS values >62% was zero. Mean TS values in the elderly group (males and females) were significantly lower (P<0. 0001) than in the blood donors group and in the hospital patients one. This observation suggests a shortened survival in the presence of (unrecognized) iron overload, pointing out at the usefulness of iron overload screening using simple biochemical tests.