Abstract Mode of interactions of three flavonoids [morin (M), quercetin (Q), and rutin (R)] with chicken blood ds.DNA (ck.DNA) has been investigated spectrophotometrically at different temperatures including body temperature (310 K) and at two physiological pH values, i.e. 7.4 (human blood pH) and 4.7 (stomach pH). The binding constants, K f , evaluated using Benesi–Hildebrand equation showed that the flavonoids bind effectively through intercalation at both pH values and body temperature. Quercetin, somehow, showed greater binding capabilities with DNA. The free energies of flavonoid–DNA complexes indicated the spontaneity of their binding. The order of binding constants of three flavonoids at both pH values were found to be K f(Q) > K f(R) > K f(M) and at 310 K.