Energy efficiency improvement is a desirable response to growing climate change and security of energy supply concerns. This article studies the impacts of a varied set of macro-level market-oriented reforms as well as structural change on economy-wide measure of energy efficiency across a group of the transition countries. These countries experienced a rapid marketization process, which, since the early 1990s, transformed their economies from central planning towards market-driven models. We use a bias-corrected fixed-effect analysis technique to estimate this effect for the period 1990 to 2010. The results suggest that reforms aimed at market liberalization, financial sector and most infrastructure industries drove energy efficiency improvements. We find significant differences in improvements in energy efficiency between transitional Central European and Baltic States, South East Europe ones and the Commonwealth of Independent States. The reasons for these differences are also discussed.