Introduction: Number of obese people is growing on a daily basis in Brazil, including morbid obese ones, but there is still a lack of studies with this subject. Due to this, the main goal of this study was to identify body profi le, physiological variables behavior and oxygen consumption in grade III obese women, submitted to an ergospirometric test in arm ergometer. Method: Take part in this study, thirteen (13) female grade III obese patients between 20 and 40 years. They were submitted to an electric bioimpedance test for body composition measurement and an Ergospirometric test in arm ergometer for oxygen consumption, heart rate, and oxygen saturation, systolic and diastolic arterial pressure, resting and after exercises, analysis. Results: The patients revealed a BMI of 46.5±3.81 kg/m², 51.9±1.59% of body fat percentage. The patients reached 168.2±4.57bpm of heart rate, didn't make any hypertensive response to the effort reaching an arterial pressure of 171.1±22.15mmHg x 87.5±4.18mmHg. Oxygen saturation was 98±0.71% and oxygen consumption peak was, also in average, 12.3±2.75ml.kg.min-1. Conclusion: It was verifi ed that there was no oxygen saturation drop nor hypertensive response and all of the patients reached the maximum heart rate.