Forty Chinchella female rabbits were purchased from Faculty of Agriculture, Mansoura University with average body weight 0.4 kg. Rabbits were raised upon well balanced ration and kept in a clean metal cages in the Animal House of Faculty of Medicine, Manssubdivided into three equal subgroups each consisted of ten rabbits.Subgroup I was given isoniazid and rifamycin, subgroup II was givenpyrazinamide and rifamycin and subgroup III was given isoniazid andpyrazinamide. All the three subgroups were given the drugs twice weeklyfor 60 days. One blood sample of about 1 ml was collected from the earvein on EDT A as enticoagulant for complete blood picture, another bloodsample of about 5 ml was collected from the ear vein and left to clot forserum separation to perform the biochemical analysis. The time of bloodsampling was performed after 15,30,60 and 90 days from the beginning ofthe experiment. Erythron mass showed no significant changes comparedwith the control group in the treated group after 15 and 30 days oftreatment. Subgroup III showed hemolytic anemia after 60 and 90 dayspost administration of the drugs.