This paper reports on the participation of ITC-irst in the Cross Language Evaluation Forum (CLEF) of 2001. ITC-irst took part in two tracks: the monolingual retrieval task, and the bilingual retrieval task. In both cases, Italian was chosen as the query language, while English was chosen as the document language of the bilingual task. The retrieval engine that was used combines scores computed by an Okapi model and a statistical language model. The Cross language system used statistial query translation model, Which is estimated on the target document collection and on a translation dictionary