Blood parameters are important indicators for health conditions in animals, but can be influenced by several factors. This study was conducted to explore reference intervals for hematological parameters and investi-gate their possible relationships with different factors in Lori-Bakhtiari ewes. A total of 96 blood samples were randomly collected from healthy ewes at a research flock. Different hematological parameters, includ-ing red blood cell, white blood cell, neutrophil and lymphocyte counts (RBC, WBC, NP and LC, respec-tively), neutrophil and lymphocyte percentages (NP and LP, respectively), hematocrit (Hct) and hemoglo-bin (Hb), mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin con-centration (MCV, MCH and MCHC, respectively) were measured at laboratory. Based on the coefficients of variations, NC (44.4%), LC (43.6%) and WBC (39.0%) were the most variable parameters, while the MCV (1.6%) had the lowest variability. Simple correlation coefficients and cluster analysis showed that erythrocyte-related parameters (Hct, MCH, MCV, Hb and RBC) were independent from the leukocyte traits (WBC, NC, NP, LC and LP). Birth type and age significantly (P<0.05) affected NC and LP, respectively. Heavier animals in 6 and 9 months of age had higher levels of Hb, MCH and MCHC in adulthood. Body weight traits also had some correlations with leukocyte parameters in higher ages, indicating that growth rate of the lambs may influence their immunity in the future or vice versa, the animals with stronger immu-nity may have higher growth rate. More attention to immunological parameters is needed, when breeding programs are planned for growth rate. پرونده مقاله