Warfarin is known to have multiple pharmacokinetic and pharmaco-dynamic interactions. The present study aimed to determine effect of azithromycin on the anticoagulant action of warfarin as well as to study the effect of warfarin on the antibacterial activity of azithromycin and to suggest the readjustment in the dose of azithromycin and warfarin when they are co-administered. In the first set of experiments, the effect of azithromycin on the anticoagulant activity of warfarin was investigated, to achieve this goal PT, CT and BT were measured. The second set of this study was conducted to evaluate the effect of warfarin on the antibacterial activity of azithromycin, to achieve this aim we used parameters measured the degree of antibacterial activity as viable bacterial count, neutrophils count, MPO activity, CRP and TNF-alpha . An interaction between azithromycin and warfarin was not observed among rats