This paper provides a brief description of a new, totally automated system for assessing metabolic and respiratory function during exercise. This system was evaluated simultaneously against two established systems, one a computer-based system and the other a semiautomated system, to determine its validity over a wide range of metabolic levels, i.e., less than 2 to greater than 16 mets. A total of 112 males and females, 12–65 yr of age, performed either arm or leg exercises on a bicycle ergometer or treadmill, starting at approximately 2 mets and progressing by approximately 1 met/min to the point of volitional fatigue. Respiratory and metabolic assessments were made each minute during the entire exercise bout. Comparisons across the three systems demonstrated remarkable agreement, particularly when all potential sources of error for each system are considered. Although several statistically significant differences between two of the systems were noted at the lowest work levels, the difference in VO2 between any two systems never exceeded 1.1 ml/kg-min.