We have typed ABO, Rh and Kell blood group systems in 1,267 voluntary blood donors native to the three districts into which Terni province is subdivided. By using the method of principal components, the Terni population was compared with those of other provinces of central Italy to disclose that (1) the Terni sample clustered with the Tyrrhenian rather than the Adriatic populations, and (2) there seems to be a positive relation with both the distribution of the languages spoken during the prehistoric period and the location of pre-Roman civilizations.