As the development of information technologies makes progress, large morphologically annotated corpora become a necessity, as they are necessary for moving onto higher levels of language computerisation (e. g. automatic syntactic and semantic analysis, information extraction, machine translation). Research of morphological disambiguation and morphological annotation of the 100 million word Lithuanian corpus are presented in the article. Statistical methods have enabled to develop the automatic tool of morphological annotation for Lithuanian, with the disambiguation precision of 94%. Statistical data about the distribution of parts of speech, most frequent wordforms, and lemmas, in the annotated Corpus of The Contemporary Lithuanian Language is also presented.