Leucocytozoonparasites remain poorly investigated in comparison to other haemosporidians. The host cell inhabited by their blood stages (gametocytes) remains insufficiently known. This study aimed to determine the blood cells inhabited byLeucocytozoongametocytes in different species of Passeriformes and to test if this feature has a phylogenetic importance. We microscopically analyzed blood films stained with Giemsa from six different bird species and individuals and used PCR-based methods for parasite lineage identification. The DNA sequences obtained were applied for phylogenetic analysis.Leucocytozoonparasite from the song thrushTurdus philomelos(cytochromeblineage STUR1), the blackbirdTurdus merula(undetermined lineage), the garden warblerSylvia borin(unknown lineage) inhabited erythrocytes, a parasite from the blue titCyanistes caeruleus(PARUS4) infects lymphocytes, while in the wood warblerPhylloscopus sibilatrix(WW6) and the common chiffchaffPhylloscopus collybita(AFR205) they were found inhabiting thrombocytes. Parasites infecting thrombocytes were closely related, while the parasites infecting erythrocytes were placed in three different clades, and the one found in lymphocytes was placed in a separate clade. This shows that the determination of host cells inhabited byLeucocytozoonparasites can be phylogenetically important and should be considered in future species descriptions. Noteworthy, phylogenetic analysis might be used for the prediction of which host cells parasite lineages might inhabit.