Immigration is one of the factors often considered as the causes of Brexit. Researchers find evidences that regions with more immigrants from the new member states of the European Union (EU hereinafter) in eastern Europe tended to vote more in favor of Brexit in the 2016 referendum. Similar relations between the size of immigrant population and anti-immigration attitudes or far-right voting are found in other richer EU member states. A common explanation for this relation is the concern that immigrants negatively affect the outcome in the host labor market. Immigration is drawing attention in Korea too. Although immigrants' share in population is still substantially smaller in Korea than in the EU, its increase is noticeable. Also, certain industries in Korea are known to be already heavily reliant on immigrant labor. Recently, as entry into the country was tightened due to the COVID-19 pandemic, firms and farms are reported to have faced a disruption in production. This trend of increasing presence of immigrants in population and in the labor market, vis-à-vis the low fertility rate and rapid aging in Korea, is raising interest and concern on the socioeconomic impact of immigration. To offer some reference for the debates related to immigration in Korea, KIEP researchers (Joe et al. 2020 and Joe and Moon 2021) look at the EU, where immigrants' presence was much higher from much earlier on, and where the greater heterogeneity among the immigrants allows for richer analyses. This World Economy Brief presents some of their findings that are salient for Korea.