The possibility of interaction of recombinant proteins of human repair DNA polymerase beta with proofreading 3' --> 5'-exonucleases TREX1 and TREX2 was investigated in vitro for the first time. The results of gel filtration analysis show the formation of a complex between 3' --> 5' -exonucleases mTREX1 and hTREX2 and DNA polymerase beta. DNA polymerase activity is shown to increase four-fold in the presence of 3' --> 5'-exonuclease TREX2. The experiments with the use of immunodot and Western blot assays on the binding of DNA-polymerase beta with 3' --> 5'-exonucleases TREX1 and TREX2 immobilized on a nitrocellulose membrane provided additional evidence on the direct association of the above proteins in complexes.