Foreign subsidiaries usually perform better than domestic enterprises, but selection effects have been acknowledged in the literature. This article contributes by quantitatively evaluating the size of the selection effects and direct effects of FDI entry. We use a large panel of firm-level data from Poland and match foreign-owned firms to a control group of non-foreign-owned companies and analyse various performance indicators. In terms of efficiency measures, between 50 and 70 percent of the foreign affiliates advantage may be attributed to direct ownership effects. However, in the case of export intensity, the majority of the differential between the domestic companies and foreign subsidiaries is attributable to selection effects: MNEs choose export-oriented companies and sectors.