Resonance light scattering technique has been employed to investigate the interaction between anthracyclines and DNA in the presence of quercetin. Upon binding to DNA, anthracyclines undergo dramatic enhancement in their resonance light scattering intensities, while quercetin goes through no obvious change in its intensity. Once being added into anthracyclines- DNA system, quercetin can induce great difference in resonance light scattering intensities between anthracyclines- DNA-quercetin ternary system and anthracyclines-DNA binary system. Consequently, the DNA binding abilities of anthracyclines can be improved by quercetin. Improved efficiency of quercetin on the interaction between anthracyclines and DNA has been calculated. Under the experimental condition, the improved efficiency values of doxorubicin, epirubicin and mitoxantrone were 38.78%, 28.53% and 16.69%, respectively. Additionally, the weak resonance light scattering intensity of quercetin-DNA system is greatly enhanced by anthracyclines and the enhanced intensity is proportional to the concentration of anthracyclines in the range 0.06-9.0 μg mL-1 for doxorubicin, 0.08-12 μg mL-1 for epirubicin and 0.01-3.0 μg mL-1 for mitoxantrone. The detection limits are 4.7 ng mL-1 for doxorubicin, 5.4 ng mL-1 for epirubicin and 1.4 ng mL-1 for mitoxantrone.