Relative hole transfer rates in DNA have been investigated in a number of nucleotide sequences experimentally. Calculation of the transfer rates in DNA is performed relying on the assumption that the transfer is realized as hopping of a hole on guanine sites, each hop being calculated on the basis of superexchange theory. It is shown that the medium reorganization energy and free energy changes play an important role in determining the transfer rate and the type of a nucleotide sequence. The results of the calculations are compared with experimental data covering a range of available sequences. (C) 2004 Elsevier B.V. All rights reserved.