AbstractBrand-new economic system has been introduced in Poland two decades ago. The economic transformation from central planning to market system had no precedent and the theory of economics had not offered any complex model of such a makeover. So, we have been all learning by doing. And now, as we want to understand the process we aim at identifying both major agents and processes that were responsible for the results achieved. Without any doubt there has been at least one important agent of the transformation that could be easily recognized, namely: individual entrepreneurship. After 1989 we have been observing numerous small enterprises being established in Poland. The SMEs sector (small and medium enterprises) after half a century of centrally planned economy has been catching up with its developments. Nowadays - as in any other market economy - SMEs are important element of economic system in Poland, too. They account for 99.8 per cent of total number of enterprises, approx. half of both capital investment and value added and roughly 1/3 of exports.The following paper aims at identify the role of the SME sector in the process of reconstruction of market system in Poland after 1989. It concentrates on one special aspect of economic transformation, namely the integration with European Union on SME development potential. To set our reasoning in order we pose the subsequent questions:What is the role of SMEs sector in Polish economy?What changes of business environment has EU integration brought?What were the costs and benefits of the integration for Polish SME sector?