Social and economic changes in Poland - due to transition of the national economy after the year 1989 - have resulted, among other things, in deep transformation of energy demand. Partly liberalised prices of energy sources have been one of the most important factors of the tendency, and have consequently led to the accumulated effects of raised costs of energy transformation, distribution and supply. It has been reflected by decreased demand for primary and secondary energy carriers and has radically corrected previous prognoses of the demand in all energy sectors, in terms of both: quality and quantity. Other important changes, including legal and ownership's issues (with impacts of new Energy Law and environment protection legislation) and latest emerging technological advantages (like broad availability of natural gas, gas turbines or gas engines in cogeneration schemes) have been added to the processes described, with additional obstacles such as financial, structural and technical measures. All of this has made the main actors of energy markets to challenge new and demanding requirements on their services and products and directed their development into partly liberalised local energy markets, which may better meat the necessity of economically efficient and environment-friendly energy and energy services supply in the future. This is quite new and unknown situation to big and monopolistic so far energy companies. The aim of the paper is to present the process of the changes and explain its possible implications for future development of energy markets in Poland and the whole region.