In the present study, we have explored the mode of binding of an anti-leukemic drug, imatinib (IMT) mesylate with DNA and resulting conformational changes in DNA double helix. UV-Vis absorption, fluorescence and circular dichroism spectroscopic techniques were employed to study these interactions. Spectroscopic results revealed that the intercalation was the primary mode of interaction between IMT and DNA. The binding constant value of 6.62 × 10(3 )M(-1) indicated the moderate interaction between IMT and DNA. Melting temperature of DNA increased from 75 to 80 °C upon interaction with IMT.