Degradation of calf thymus and plasmid DNAs was studied by means of conventional as well as adsorptive transfer stripping voltammetry in cyclic and sc. modes in combination with an HMDE. These techniques detected sensitively small damages to the DNA double helix induced by relatively low doses of ionizing radiation as well as by partial depurination of DNA at a weakly acidic pH in the presence of HNO2. Electrochemical analysis did not require any special pretreatment of the sample, and the amount of DNA necessary for this analysis was below 1 mu g. It was shown that dissolving DNA in concentrated perchloric acid resulted in a deep DNA degradation including depurination of DNA.