Abstract: Themain pattern and causes of the alteration in blood biochemistry indices incoccidia-infected broilers were studied with principal component analysis. The resultshowed that infection with Eimeria spp. mainly affected levels of serum protein andlipids. Variability of serum indices was related to the parasitic site and pathogenicityof strains (or lines) with which the chickens were infected.The strain which had the mostprofound effect on the serum constituents was E. acervulina,E. tenella parent line came innext,while the effect of E. maxima precocious line on blood indices was least. Thecharacteristic changes in the serum of E.tenella and E. maxima precocicus line groups wasalteration in serum lipids.Infection with E. tenella and E. acervulina parent lineaffected lipids and proteints to the same extent.