The inclined stepper is a novel piece of exercise equipment that is designed to offer precise control over a wide range of loading levels and exercise speeds by simulating an inclined stepping motion (21). The purpose of this study was to evaluate the relationship and test-retest reliability of the stepper ergometer. Twenty-eight healthy volunteers (age: 23.5 ± 3.6 yrs) completed a graded treadmill (TM) and two graded, step (SI, SII) ergometry tests to assess maximal oxygen consumption (V̇O₂max). The order of these tests was randomized. Expired gases were analyzed using the Medical Graphics CPX/D metabolic cart. V̇O₂max between SI (V̇O₂ = 2.57 L/min) and SII (V̇O₂ = 2.65 L/min) revealed an correlation of r=.91. The S trial with the highest V̇O₂max value for each subject was used to compare with the TM. A one-way ANOVA was performed on the cardiopulmonary and perceptual data. Mean values and SD for the best stepper were: HRmax = 183 ± 10.0 bpm, V̇O₂max = 2.6 ± 0.6 L/min, RER = 1.27 ± 0.07, RPE = 17.1 ± 1.6. Mean values and SD for the treadmill were: HRmax = 193 ± 8.8 bpm, V̇O₂ max = 3.2 ± 0.8 L/min, RER = 1.15 ± 0.04, RPE = 17.8 ± 1.4. Construct validity showed that the percentage of tests that achieved maximal test criteria for heart rate was 96%; for RPE was 46% and for RER was 100%. These findings indicate that the inclined stepper elicits a significantly lower cardiovascular and metabolic response at maximal exercise as compared to the treadmill. In addition, the data suggests that this modality has many desirable features for assessment in the laboratory and use in the fitness arena.