A system for large vocabulary continuous speech recognition of Slovenian language is described. Two types of modelling units are examined: words and sub-words. The data-driven algorithm is used to automatically obtain word decompositions. The performances of one-pass and two-pass decoding strategies were compared. The new models gave promising results. The recognition accuracy was improved by 2.5% absolute at the same recognition time. On the other hand we achieved 30% increase in real time performance at the same recognition error.