Cardiac troponin (cTnI) and erythrocyte distribution width (RDW) have been used as specific markers for the evaluation of cardiac arrhythmias and myocardial diseases. In this experimental study, we aimed to determine the dose-dependent administration of an Essential OilMixture (EOM) (Eucalyptus globulusLabill, Thymus vulgaris, Cymbopogon nardus, and Syzygiumaromaticum) on the serum erythrocyte indices and myocardial damage. We used 400 male, oneday-old, Ross-308 chicks. Each group ((n=8) (22°C Control (C), C+250 mL/1,000 L, C+500 mL/1,000 L, C+750 mL/1,000 L), 36°C (stress control (SC), SC+250 mL/1,000 L, SC+500 mL/1,000 L, SC+750 mL/1,000 L) was further divided into eight groups with 50 animals. Each group of 50 chicks was further subdivided into five groups with 10 animals in each compartment. The results showed that the WBC, RBC, HGB, HCT, RDW-SD, RDW-CV, and Lymphocyte decreased in groups without exposure to temperature stress (22ºC) compared to the 22ºC control group; whereas, CnTnI, MCHC, NEUT, and IG (p<0.05) increased compared to the control group. In groups exposed to temperature stress (36ºC), the WBC, HGB, HCT, RDW-SD, and Lymphocyte decreased compared to the control group, but MCH, MCHC, NEUT, and IG increased compared to the control. However, cTnI, CK, creatinine, RBC, and RDW had no effect on CD, MONO, EO, and BASO (p<0.05). EOM mixture had no effect on hematological and biochemical parameters.