Subject access to bibliographic data supported by knowledge organization systems, such as subject headings and classification, plays an important role in ensuring the quality of library catalogues. It is generally acknowledged that users have a strong affinity to subject browsing and searching and are inclined to follow meaningful links between resources. Research studies, however, show that library OPACs are not designed to support or make good use of subject indexes and their underlying semantic structure. A project entitled OPAC semantici was initiated in 2003 by a number of Italian subject specialists and by the Gruppo di ricerca sull’indicizzazione per soggetto (Research Group on Subject Indexing)(GRIS) with the aim of analysing and evaluating subject access in Italian library catalogues through a survey of 150 OPACs. Applying the same methodology, a follow-up survey to assess whether any improvement had taken place was conducted five years later, in spring 2008. The analysis of these two surveys indicated that there was a slight improvement. The authors discuss the results of the two surveys and analyse the problems in subject searching in OPACs. Using the example of Italian OPACs, the authors make some specific considerations on the two-step subject search recommended by the GRIS and explain how this can be achieved through authority control.