Although sport-physiologists have repeatedly analyzed respiratory gases through exercise, it is relatively new in the cardiovascular field and is obviously more acceptable than standard exercise test, which gives only information about the existence or absence of cardiovascular diseases (CVDs). Through the new method of exercise test, parameters including aerobic and anaerobic are checked and monitored. 22 severe cases of heart failure, who were candidates of heart transplantation, referring to Massih Daneshvari Hospital in Tehran from Nov. 2007 to Nov. 2008 enrolled this study. The study was designed as a cross-sectional performance and evaluated only patients with ejection fraction less than 30%. O2 mean consumption was 6.27±4.9 ml/kg/min at rest and 9.48±3.38 at anaerobic threshold (AT) exceeding 13 ml/kg/min in maximum which was significantly more than the expected levels. Respiratory exchange ratio (RER) was over 1 for all patients. This study could not find any statistical correlations between VO2 max and participantsʹ ergonomic factors such as age, height, weight, BMI, as well as EF. This study showed no significant correlation between VO2 max and maximum heart rate (HR max), although O2 maximum consumption was rationally correlated with expiratory ventilation. This means that the patients achieved maximum ventilation through exercise in this study, but failed to have their maximum heart rate being led probably by HF-induced brady-arrhythmia or deconditioning of skeletal muscles.