The objective of this study was to measure stress levels in broilers raised on a pasture production system (PPS) and a conventional production system (CPS) by evaluating lymphoid organ weights, white blood cell profiles (WBCP), total white blood cell counts (TWBC), and heterophil to lymphocyte ratios (HLR). Broilers were brooded indoors for 3 weeks then divided into 2 groups; one placed on pasture while the other remained indoors. Blood was collected at weeks 3, 5, and 7 via brachial venipuncture. After 49 days, birds were slaughtered and lymphoid organs harvested. Results showed no differences between treatments for lymphoid organs, TWBC, or WBCP. Eosinophils were higher (P < 0.05) in CPS (333.33) compared to PPS birds (148.00) at week 5. The HLR was lower (P < 0.05) in PPS broilers at week 5 (0.40) than weeks 3 (0.44) and 7 (0.43). The PPS broilers experienced less stress overall than CPS birds.