The change in respiratory volume during exercise because of the use of different types of respiratory apparatus has previously been reported in the literature. However, to our knowledge, there has been no report of the reliability of measurement for commonly used apparatuses. The purpose of this study was to compare the reliability of the Hans Rudolph 2700 NRB valve with the Vacumed Speak‐Easy Mask II during maximal exercise testing. Eight moderately trained college‐aged women performed two maximal graded exercise tests using each apparatus. Breath‐by‐breath measurements of pulmonary variables were collected and a moving point average displayed, every 15 seconds. A MANOVA (valve×trial×subject) revealed no significant difference (p>0.05) in oxygen consumption, respiratory exchange ratio, rating of perceived exercise, minute ventilation (VE), tidal volume (Vt), or breathing frequency (fB) between the two pieces of equipment. Intraclass reliability of breath‐by‐breath measurements of VE, Vt, and fBwas higher overall at each work rate for the Hans Rudolph valve. A greater unexplained error variance was attributed to the Speak‐Easy Mask. Although no significant measured volume difference existed between the two types of apparatuses, it is recommended that in an experiment determining group mean statistics the number of subjects be increased in order to improve the reliability of the measurements.