Five morpholino-quinazoline derivatives have been investigated voltammetrically using a competition with the tris(o-phenanthroline) cobalt(III) redox marker for the accumulation at dsDNA modified screen-printed electrodes. An association of quinazolines with DNA was observed at the modified electrodes polarized by the negative potential of -0.4 V vs. Ag/AgCl. This was confirmed by a potentiometric stripping analysis based on the DNA guanine signal. Calibration curves for quinazolines within a concentration range of micromol/L were obtained with DP voltammetry using 5 x 10(-7) mol/L Co(phen)3(3+) marker. The quinazolines exhibit no effect on the DNA complex with the fluorescent thiazole orange derivative TO-PRO-3. The role of the accumulation potential in the association interaction with DNA is discussed.