The empirical analysis performed with the help of risk scenarios shows that the level of gas supply security in the region cannot be evaluated based only on the infrastructure standard N-1 indicator, which mostly considers external factors. Since there are considerable internal risks e.g. the capacity of cross-border gas metering stations, risk scenarios or similar methods of risk analysis have to be used to evaluate the level of security of gas supply. The complex solution should be applied – infrastructure standard and risk scenarios or similar methods of risk analysis, as well as the existing N-1 indicator’s calculation formula has to be modified in order to take into account internal factor (capacity of system elements).