The author made a morphological and biological comparison between the population of Argas (A.) polonicus Siuda, Hoogstraal, Clifford et Wassef, 1979 from Poland and the population of that species from Czechoslovakia, denoted in previous author's papers as Argas (A.) vulgaris Filippova, 1961. The comparison of morphometric features as well as the results obtained in the studies of those argasids in SEM have demonstrated some statistically significant differences which the author evaluates as intraspecific adaptive variability and does not attach any taxonomic importance to them. Experimental hybridization of P1 and F1 generations in both populations has not suggested any genetic incompatibility. A few differences in the developmental cycle of homogamic crosses in the Polish tick population is likely to be the consequence of the adaptation of this population to different living conditions. Due to the lack of taxonomically valuable differences the author includes the members of the Czechoslovak population of these argasids in the species A. polonicus.