en Occupational Health Original Article <span style="font-family:arial;"><strong>Background:</strong> Assessment of aerobic capacity is of vital importance in both general community and occupational settings. Valid, reliable and feasible tests are required to indicate the functionality of cardiopulmonary system. The present study was carried out aiming to evaluate the suitability of the Chester step test (CST) as a field test to measure the Iranians&rsquo; aerobic capacity.&nbsp;&nbsp;&nbsp;<br> <strong>Materials and Methods:</strong> In this descriptive study performed in 2016, 63 university students completed the Astrand-rhyming cycle ergometer test and the CST. Actual and predicted maximum rate of oxygen consumption (VO₂ max) were recorded and their relationship was examined by Pearson&#39;s correlation coefficient and Bland-Altman plot. Repeatability was checked using intra-class correlation coefficient (ICC).&nbsp;<br> <strong>Results:</strong> Predicted and actual amounts of VO₂max were significantly correlated (r = 0.868, P < 0.001). The mean difference between them was -0.89 ml/kg/minute. ICC between CST and the retest CST (CST_retest) was 0.858.<br> <strong>Conclusions:</strong> CST is a valid and reliable field test for the estimation of cardiorespiratory capacity among the study subjects. With its exclusive features (e.g. safety, convenience and ease of use), CST could be suggested as an alternative to other existing methods of estimating VO₂max; the applicability of the existing methods among Iranian individuals are unclear. However, like other estimation methods, special prudence should be adopted when dealing with critical health decisions.</span> Validity,Students,Iran, 37 43 http://johe.rums.ac.ir/browse.php?a_code=A-10-260-1&slc_lang=en&sid=1 Mahnaz Saremi m.saremi@sbmu.ac.ir 22400319475328460010529 22400319475328460010529 Yes Department of Ergonomics, School of Health, Safety and Environment, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Shahid Beheshti University of Medical Sciences Fatemeh Khayati saremim@yahoo.com 22400319475328460010530 22400319475328460010530 No School of Health, Safety and Environment, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Shahid Beheshti University of Medical Sciences Fatemeh Mousavi saremim@yahoo.com 22400319475328460010531 22400319475328460010531 No School of Health, Safety and Environment, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Shahid Beheshti University of Medical Sciences