Аннотация:In this paper we present an approach of introducing thesaurus information into probabilistic topic models. The main idea of the approach is based on the assumption that the frequencies of semantically related words and phrases, which met in the same texts, should be enhanced and this action leads to their larger contribution into topics found in these texts. The experiments demonstrate that the direct implementation of this idea using WordNet synonyms or direct relations leads to great degradation of the initial model. But the correction of the initial assumption improves the model and makes it better than the initial model in several measures. Adding ngrams in similar manner further improves the model.