The content of constitutive from of 70 kDa family heat shock pritein (Hsp70) was determined by the method of immunoblotting. 9 strains of representatives of the genus Acanthamoeba including 8 amphizoic (facultative parasitic) strains and one free-living (isolated from upper horizons of Arctic soils) were studied. We also examined 15 strains of free-living freshwater amoebae of various geographic origin, age and species. 14 of them belonging to the genus Amoeba and one to the genus Trichamoeba. The presence of Hsp70 was demonstrated in the cells of all 25 freshwater amoeba strains, whereas it was shown only for 2 of amphizoic acanthamoebae strains. In all these cases, the position of zone at the blot, revealed by monoclonal anti-HSP70 antibodies, corresponded to polypeptide with molecular mass about 70 kDa. We also found rather high level of constitutive Hsp70 in the cells of contemporary free-living tundra soil representative. However, in this case, the stained zone occupied the position corresponding to MW about 60 kDa which was just the same as earlier obtained for the ancient tundra acanthamoebae strain from permafrost.