In the last decade, genes important for proper immune response have become subject of great interest even outside the model vertebrates. Most of the studies on this topic deal with Major histocompatibility complex (MHC) genes, which represent a crucial component of the vertebrate acquired immune system. The MHC genes encode transmembrane proteins for antigen binding and recognition by T-cells, thus triggering an immune response. In some species, evidence has been found for these genes being important also when choosing mates. On the other hand, very little is known about other type of immunity genes in wild vertebrates, e.g. the Toll-like receptors (TLR), which are an important part of innate immunity. So far, there are no data about any linkage between the TLRs and reproductive success in birds. The aims of this study will be: 1) bibliographic search for all available information on the structure and diversity of TLRs and other genes of innate immunity in birds 2) looking for the possible linkage between their variation and fitness in birds Financial support of the research is provided by two projects of the Czech Science Foundation (2008-2012 and 2010-2014).