Over the last decades, some major accidents have occurred in highly reliable industries such as petrochemical plants. Probably, sophisticated safety management systems and a high level safety culture have contributed to decreasing the number of usual accidents, but these classical approaches may not have been sufficient to prevent the occurrence of extraordinary incidents and accidents. Consequently, there is a need for new approaches like resilience engineering to promote the safety of these systems. In this light, and to use safety culture more efficiently in ultra-safe systems, a new concept as "resilience safety culture" has been proposed. However, due to the paucity of studies and their qualitative nature, there is now more interest in using numerical methods to quantitatively evaluate the resilience safety culture of a system. This research, however, aimed at a quantitative assessment of resilience safety culture of a petrochemical plant using a questionnaire and was based on the two approaches of principal components analysis (PCA) and numerical taxonomy (NT). Accordingly, a questionnaire including 59 questions about several aspects of the safety culture and resilience engineering was designed and distributed to 354 randomly selected employees of 12 units in a petrochemical plant. The results of exploratory factor analysis of the data extracted thirteen factors which represent the resilience safety culture. The analysis also led to the determination of the score of resilience safety culture and its weakness in the petrochemical units. Implementing the proposed approach would enable the policy makers and managers in petrochemical industries to identify current weaknesses and challenges regarding the resilience safety culture in their system. (C) 2016 Elsevier Ltd. All rights reserved.