Recent initiatives encourage the reduction of sodium in foods to improve consumer health. Blue cheese contains approximately 370 mg sodium per 28 g serving, 16% of the daily recommended value of sodium and twice the amount found in a serving of Cheddar (21 CFR 101.9 (c)(9)). However, salt is essential for control of blue cheese enzymatic and microbial activity during ripening (Morris, 1981). One way to maintain this control in cheese is to reduce sodium and implement a molar replacement of NaCl with KCl. Because blue cheese is often surface-salted, the effects of sodium reduction may be more noticeable in the center of the cheese wheel as the salt and moisture equilibrate from the surface to the center during aging (Cantor et al., 2004). The purpose of this study was to evaluate the effects of 25% sodium reduction on blue cheese composition, flavor, sensory, and proteolytic properties with and without the use of potassium chloride (KCl) at two locations in the cheese wheel. Three-kg wheels of pasteurized milk blue cheese were produced from 2,100 kg of milk (in duplicate), and three salting treatments were applied to an equal number of randomly selected wheels. Salt was applied by % weight of the wheel in the following treatments: Control (3.5 wt% NaCl), reduced sodium (2.63 wt% NaCl), and reduced sodium with KCl (2.63 wt% NaCl, 1.17wt%KCl). Wheels were evaluated monthly during 5 months of aging, sampling both inner and outer portions of the cheese wheel. Sodium and potassium concentrations, fat, moisture, pH, aw, volatile free fatty acids, and extent of proteolysis (as measured by free amino acids) were measured. Sensory attributes and volatile flavor chemicals were measured at months 3 and 5. Salt reductions of 23% and 21% in reduced with KCl and reduced treatments, respectively, were achieved. The water activity of control and reduced with KCl treatments was the same during aging, while the reduced treatment had higher aw. A greater extent of proteolysis was observed in inner samples as compared to outer wheel samples, with reduced treatments trending (though not significantly) higher than control or reduced with KCl. A descriptive sensory panel found higher overall flavor intensity and 12 contributing aroma or flavors which were more intense in the inner portion of the cheese compared to outer portions (P<0.01). Many sensory attributes were also different between salting treatments as evaluated by the descriptive panel. Concentrations of free fatty acids varied between location and treatment for some acids, though medium chain free fatty acids were unaffected by salting treatment. Flavor volatiles associated with blue cheese were found in higher concentrations in reduced treatment and inner wheel samples, specifically 2-heptanone, 2-pentanone, ethyl hexanoate, and methyl propanoate. A consumer panel (n=95) ranked overall liking for all treatments similarly, and higher texture liking for reduced with KCl. These data suggest sodium reduction in blue cheese (up to 25%) with and without molar replacement by KCl can result in a blue cheese which is equally acceptable to the consumer, despite some compositional and sensorial differences. These results hold true for full sodium blue cheese with approximately 1200mg Na/100g cheese. Because of the extensive differences noted between inner and outer wheel, where sodium concentrations differed for the first 61 days of aging, and because reduced sodium treatment cheeses were often distinguishable from control and reduced with KCl, reducing the sodium of blue cheese to a larger extent than 25% may result in loss of product quality or safety.