As part of a continuing effort to improve U.S. Army combat clothing and equipment, four proposed Intermediate Cold-Wet Boots and the standard-issue U.S. Army Cold-Wet Vapor Barrier Boot were evaluated during a controlled chamber study to determine human physiological responses while sedentary and while performing intermittent exercise in simulated cold-wet conditions. The results showed that a dry, rubber, vapor-barrier boot provided increased foot protection while subjects were sedentary in a moderately cold environment. New leather footwear incorporating vapor-permeable, waterproof membranes were incapable of maintaining a dry interior after the boot had been subjected to a prolonged soak in shallow water. This moisture ingression increased boot weight and caused minor, albeit immobilizing injuries during intermittent exercise.