Only 20 years ago, Poland was self-sufficient in pig production, being one of the key players in the European pig market. Since then a growing specialization of Poland in pig finishing and meat processing has been observed, while the domestic production of piglets has declined. As a consequence, Poland has lost its self-sufficiency in pig production and become strongly dependent on imports of piglets, mainly from Denmark. The aim of this paper is to summarize the evolution of the Polish pig industry and specify the main determinants of the Polish imports of Danish piglets. The results of the estimates using the vector error correction model (VECM) show that the volume of the Polish imports of piglets from Denmark may be explained by a degree of specialization of Poland in pig finishing, the phase of pig cycle, and the competitiveness of Polish pork. The results may be helpful in understanding the evolution of the Polish pig industry and its growing dependence on imports of piglets.