Based on our knowledge, there have been no studies about the effect of age, sex, lobe and slaughtering stress on cellular distribution of bronchoalveolar lavage fluids in calves and cattle in Iran. Objectives: The main purpose of this study was to compare the cell distribution pattern of bronchial alveolar lavage fluids in calves and cattle in terms of age, sex, type of lung lobes and the stress of slaughtering. Methods: Bronchoalveolar lavage was performed in twelve calves at three different ages' groups (less than 2 months, 2-4 months and 4-6 months). 250 milliliters sterile normal saline was infused through the tracheal tube and lavage was performed using syringe pressure. Post-mortem BAL was performed on twelve isolated lungs by infusing 150 milliliter normal saline. The lavage fluid was collected in sterile plastic tubes. The slide smears was prepared by pellet which were air-dried and stained with a Giemsa stain. Slides were evaluated cytologically. The data was analyzed by T-test, One Way ANOVA and post hoc Tukey test .Also, the Spearman correlation coefficient was used to assess the age and cell. Results: Significant negative correlations were observed between cells such as epithelial cells, macrophages and mast cells, with a correlation coefficient of -0.430, - 0.059 and- 0.267- and age although the differences were not significant (p<0.01). Statistically significant difference was observed in percentages of mast cells in males (1.48±1.25%) and females (zero percent) (p=0.04 ). The differences were significant (p=0.019) between percentage of epithelial cells in the lungs of slaughtered cattle and lavaged lung of calves. The percentages of macrophages in slaughtered animals was significantly decreased (p=0.019) compared with live calves. Significant differences were not observed in cell density in different ages and sexes. But in the cell density in live animals (583 cells per microliter) was significantly higher than the lungs of slaughtered (237 cells per microliter) (p=0.03). Conclusions: It seems that age and lobe do not affect pattern of lung immune cells. Sex and slaughtering stress, however may cause changes in immune cell type and density and lead to develop more respiratory disease.