Purpose: To evaluate the metabolic cost of varying aquatic treadmill (ATM) exercise speed and water-jet resistance and compare with land treadmill (TM) conditions at similar running speeds. Methods: 15 participants (7 men, 8 women, age 22 + 4 years, height 173 + 8 cm, weight 66.9 + 9 kg) submerged to the xiphoid process completed nine 5-min submaximal ATM trials at 174-, 201-, and 228-m/min treadmill speeds with water-jet resistances set at 0%, 50%, and 75% of capacity. Oxygen consumption (VO2), expired ventilation (VE[BTPS]), tidal volume (VT), breath frequency (f), heart rate (HR), oxygen (O2), pulse, and ratings of perceived exertion (RPE) were recorded during each trial. The corresponding TM speeds that yielded VO2 costs similar to ATM conditions were determined. Repeated measures ANOVA and paired t tests were employed to determine significance (p < .05). Results: Increasing running speed and water-jet resistance both significantly increased VO2, HR, VE, (VE[BTPS]), pulse, and RPE. Women were lower (p < .05) than men in VO2, (VE[BTPS]), O2, pulse, and VT, and higher in HR and f in all ATM trials. Comparable (p < .05) metabolic costs (VO2) were observed when TM speeds were similar to ATM speeds without jet resistance. The addition of jet resistance increased (p < .01) the land TM required to elicit a similar metabolic costs by 27.8 and 54.6 m/min, respectively. Conclusions: These results suggest ATM yields similar metabolic costs to land TM in running speeds of 174-228 m/min.