Аннотация:The state of bird fauna of Lake Baikal throughout the last 150 years (the late XIX - early XXI centuries) is analyzed on the base of the authors’ own long-term researches and literature data. 396 species have been reported from the Lake Baikal over the entire history of studies. Significant changes in species composition are registered in comparison to the middle of XX century. 321 species were recorded during the extensive researches in 1950-1960th. 391 species are reported here, with 5 species excluded from the list, and 75 registered as new since the previous inventory. The most of new species were immigrants from south-east, though the colonization went from different directions. The great changes were recorded in the overwintering group of species: the number of wintering birds increased from 82 to 121 species. The changes in the fauna may be explained by several reasons; the most important are climate changes and decreased agricultural activities.