Dried whey and whey protein are important food ingredients. Functionality of whey products has been studied extensively. Flavor inconsistency and flavors which may carry through to the finished product can limit whey ingredient applications in dairy and nondairy foods. The goal of this research was to determine the flavor and flavor variability of commercially produced liquid Cheddar cheese whey. Liquid Cheddar cheese whey from five culture blends from two different stirred-curd Cheddar cheese manufacturing facilities was collected. Whey flavor was characterized using instrumental and sensory methods. Wide variation in whey headspace volatiles was observed between different manufacturing facilities (P<0.05). Hexanal and diacetyl were two key volatiles that varied widely (P<0.05). FFA profiles determined by solid-phase microextraction and degree of proteolysis of the whey samples were also different (P<0.05). Differences in whey flavor profiles were also confirmed by descriptive sensory analysis (P<0.05). Differences in liquid whey flavor were attributed to differences in milk source, processing and handling and starter culture blend. The flavor of liquid Cheddar cheese whey is variable and impacted by milk source and starter culture rotation. Results from this study will aid future studies that address the impact of liquid whey flavor variability on flavor of dried whey ingredients.