This paper presents the main results of a comprehensive assessment of GHG mitigation options in Ukraine. The primary focus is the energy sector. According to the prognosis of the baseline scenario, which assumes that the GDP reaches the level of 1990 in the 2005-2010 period, net GHG emissions would exceed the 1990 level by around 2005. The baseline scenario includes implementation of national programs to promote the adoption of technologies and practices that improve the efficiency of energy use. A mitigation scenario was created that includes widespread adoption of such technologies and practices in all sectors. Energy-saving technologies play the most important role in reducing emissions in this scenario. Relative to the baseline scenario, net GHG emissions in 2015 are 46% lower. The estimated incremental capital investment required for the mitigation scenario is $30-35 billion.