The assemblage of lacustrine ostracods found in the Eemian Interglacial sediments at Kruklanki (Masurian Lake District, northeastern Poland) contains 18 species belonging to 13 genera. The most dominant species are Candona neglecta Sars, 1887, Limnocytherina sanctipatricii (Brady et Robertson, 1869), Limnocythere inopinata (Baird, 1843) and Candona candida (O.F. Müller, 1776). Cyclocypris serena (Koch, 1838), Ilyocypris decipiens Masi, 1905, Pseudocandona insculpta (G.W. Müller, 1900) and Leucocythere mirabilis Kaufmann, 1892 are recorded for the first time from the Eemian of Poland; the latter two species are also new for the Eemian lacustrine deposits of Europe. The ecological requirements of the recognised ostracod species as well as their geographic ranges in the Quaternary of Europe are summarised. Based on these data, past habitat type is estimated as a deeper littoral of a lake with reasonably cold, well-oxygenated and calcium-rich waters. The present state of knowledge of the Eemian ostracods from Poland is reviewed and their comparison with the Eemian ostracod assemblages from Europe is briefly given. Comparison of the ostracod faunal assemblage from Kruklanki with those from other Eemian sites in Poland enables to establish and describe one general type of ostracod assemblages characteristic for lacustrine littoral in this interglacial.