This article aims at evaluating the historical determinants and implications of Turkey's natural gas import dependency. We implement principle component analysis (PCA) methodology to construct a natural gas import vulnerability index (NGIVI) for the period between 1986 and 2014 using five factors: (1) the share of natural gas in primary energy consumption, (2) the share of natural gas in primary energy imports, (3) the non-diversification of natural gas import sources, (4) the share of LNG in total natural gas imports, and (5) natural gas import prices. Results reveal that the first two factors have always dominated the NGIVI, while the others were consequential but different times. Turkey's NOM increased until 2008, when it peaked, and remained relatively flat since then, indicating neither an improvement nor a worsening in its vulnerability. We also compared the NGIVI with the oil import vulnerability index (OIVI) of Turkey, constructed in 2011 by the authors. Although there has been a remarkable decline in the OIVI since the mid-1980s, the NGIVI has remained high until the present day. This result could be attributed to Turkey's different historical experience in importing oil and natural gas. (C) 2018 Elsevier Ltd. All rights reserved.