The poultry industry is seeking an advanced chilling system that can improve chilling efficiency, microbial safety, and water consumption without compromising meat quality. The objective of this study was to evaluate the effects of sub-zero saline chilling methods on chilling efficiency, breast fillet tenderness and microbial reduction of broiler carcasses. Following evisceration and rinsing, broiler carcasses were randomly assigned to one of three chilling solutions: 1) 0% salt or ice water control (0% NaCl/0.5oC), 2) 3% salt (3% NaCl/-1.8oC), and 3) 4% salt (4% NaCl/-2.41oC) solutions. Broiler carcasses in sub-zero saline solutions reached the target internal temperature of < 4.4 oC in a faster rate than the 0% salt control, reducing the chilling time by 11% and 39 % for 3% NaCl/-1.8oC and 4% NaCl/-2.41oC solutions, respectively. There was no significant difference in breast fillet pH, regardless of chilling treatment (P < 0.05). However, the breast fillets from sub-zero saline solutions showed higher R-value and longer sarcomere length than those of control fillets (P < 0.05). Breast fillets excised from carcasses in 4% NaCl/2.41oC were significantly tenderized more than the control fillets, with an intermediate tenderness observed for the fillets from 3% NaCl/-1.8oC (P< 0.05). Before chilling, broiler carcasses contained mesophilic aerobic bacteria (MAB), Escherichia coli(E. coli), and total coliforms for 3.81, 0.78, and 1.86 log colony forming unit (CFU)/g, respectively. After chilling, the populations of E. coliand total coliforms were significantly reduced on the carcasses in 3% NaCl/-1.8oC and 4% NaCl/-2.41oCcompared to the control fillets (P< 0.05). There was no significant difference for MAB populations, regardless of treatment. Based on these results, chilling of broiler carcasses in 4% NaCl/-2.4 °C solution seems to be the best choice to improve chilling efficiency, meat tenderness, and microbial reduction compared to the control (0% NaCl/0.5ºC) and 3% NaCl/-1.8oCsolutions.