The article is an attempt to compare the positions of the SMEs sector in Poland and in the European Union. To this end, respective shares of the SMEs sector in, inter alia, the total number of enterprises, generation of value added, the number of employed persons, as well as their development trends have been compared. The analysis shows that in Poland the position of the sector of small and medium-sized enterprises has been improving. As a consequence of that, there has been a convergence between SMEs sectors in Poland and in advanced market economies. At present, this sector already plays a dominating role in Poland, thus having a decisive impact on the situation and development of the country’s entire economy. The position assumed by the small and medium-sized enterprises’ sector in Poland has already approached the EU average, and in terms of some measures, like value added generation, it has even exceeded that level. In the European Union small and medium-sized enterprises usually hold a dominating position in the same sectors of the economy as in Poland. Nevertheless, among the seven major sectors of the economy (excluding agriculture, forestry fisheries, public administration and non-market services) they play the most significant role in construction and not in trade. Both in Poland and in the European Union the SMEs sector is characterized by a low propensity to export and by low labour productivity. Thanks to the latter, it has a positive effect on the labour market equilibrium.