Celestine blue (CB) was introduced as a new electroactive indicator in DNA biosensors. The interaction of CB with DNA was investigated by electrochemical and spectroscopic methods. The effect of buffer kind and pH on the electrochemical behavior of CB was studied. The peak currents of CB were linearly related to DNA concentration in the range of 5.0×10 −9 to 1.0×10 −7 mol/L. The detection limit of this approach was 4.76×10 −10 mol/L. Based on spectrometry data a hypochromic effect was observed in UV-Vis spectra of CB with increasing DNA concentration. The results illustrate the possible interaction mode between CB and DNA is electrostatic binding. celestine blue, differential pulse voltammetry, DNA biosensor, electroactive indicator