This paper assesses the natural gas supply security of 23 importing countries from divergent regions of the world for the period between 2001 and 2013. The indicators used for the study are the volume of imported natural gas, the number of natural gas suppliers, the level of dependency on one country, import dependency, the fragility of supplier countries, and the share of natural gas in primary energy consumption. The method used to establish the supply security index is the PCA (principal component analysis) over the indicators in the model for each country on a yearly basis for the period 2001 to 2013. The dispersed country sample enables the established index to measure the sensitivity of specific natural gas importer countries using a uniform framework. According to the results, the most effective indicators for the measurement of supply security are the number of supplier countries, supplier fragility, and the overall volume of imported gas. (C) 2014 Elsevier Ltd. All rights reserved.