Adriamycin, a cancerostatic anthracycline antibiotic, causes considerable death of tumour cells, together with the induction of breaks in DNA single and double strands. The interaction of this compound with DNA was investigated using an electrochemical DNA-biosensor. Adriamycin intercalation in DNA disrupts the double helix and the detection of guanine and 8-oxoguanine could mimic one possible mechanism for the in vivo adriamycin drug action.