Labor productivity has a significant impact on time, cost, and quality of a construction project. Especially the competitive environment of the construction industry forces construction companies to increase their labor productivity values in order to keep their positions in the industry. In this respect, identification and evaluation of factors that affect the labor productivity becomes a crucial issue for industrial practitioners. In the academic literature, there are many studies that investigated these factors and their relationships with the labor productivity. In these studies, the factors were categorized under different groups and ranked according to their importance levels. However, in most of these studies, both the standard deviation among these factors under the same group and the mean value of each group were neglected. In addition, perspectives of managers were taken into account in general while those of craft workers were ignored. The aim of the current study is to re-evaluate the factors under the same groups by considering their standard deviations and mean values from the craft workers' point of view. For this purpose, after a detailed literature review, 37 factors were identified and categorized under four groups such as organizational, economical, physical, and socio-physiological factors. A questionnaire survey were then applied to craft workers to obtain the necessary data which was analyzed by means of the Relative Importance Index (RII) technique. The results revealed that, although the ranking of the factors remained the same, their importance levels have changed. (C) 2016 The Authors. Published Elsevier Ltd.