The previous study of indomethacin-​quercetin (IM-​QRT) compatibility by thermal anal. was continued in presence of different ratios of QRT to investigate the effect of QRT on the polymorphic structure of IM.  Thermal anal. results revealed that the compatibility of phys. mixts. and co-​ppts. were at all ratios and slight formation of polymorph II of IM in all ratios of co-​ppts.  Also, UV-​spectra investigated the compatibility and possibility of quant. anal. of IM in presence of QRT.  The synergistic effects of QRT on IM were studied using hot plate and p-​benzoquinone methods for analgesic activity in mice and yeast-​induced inflammation for anti-​inflammatory effect in rats.  QRT was found to have the ability to increase the duration of analgesic activity of IM.  Also, the reaction time of IM-​QRT combination increased significantly to reach the max. after 4 h.