This paper presents a computable general equilibrium model of the Polish economy. The POLGEM model belongs to the well-known ORANI family of CGE-models. The paper gives an overview of the model database and highlights the innovations over the standard ORANI model that have been implemented. In particular, we introduce a distinction between imports from and exports to several sources. The report also presents the results of an application of the model to evaluating the effects of Polish accession to the EU. We analyse the effects of trade liberalisation, tax harmonisation, and the repercussions of introduction of the structural fund transfers. Harmonisation affects relatively few sectors of the Polish economy. The impacts of structural funds dominate We find the overall effects of accession to be favourable on the Polish economy but inevitably, not all sectors of the economy will benefit from EU membership.