Abstract: The purpose of this study was to test the utility of transthoracic electrical bioimpedance (TEB) in evaluating cardiac responses to maximal cycle exercise in healthy adult females. Thirty college women (age 23.8±3.9 yrs.), following a baseline resting evaluation, performed an upright maximal cycle ergometer test until exhaustion. Throughout testing, cardiac output (CO) and oxygen consumption were measured simultaneously by transthoracic bioimpedance cardiography (NCCOM3–R7, BoMed, Irvine, CA) and open circuit spirometry indirect calorimetry (OCM2, Physiodyne, Farmingdale, NY), respectively. Satisfactory CO readings were obtained throughout exercise in 26 of 30 subjects and they were highly related to directly measured oxygen uptake (mean individual r=0.97, SD=0.03). However, absolute CO values were higher when compared with previous studies using other standard invasive methodologies. It is concluded that TEB can be a useful, safe and non-invasive technique to measure relative changes in CO to maximal cycle exercise in healthy adult females.