One of the most important determinants of the success of intranet sites is their degree of usability. This study aims to contribute towards intranet design guidelines for usability through an empirical investigation using an existing 'live' site and realistic tasks. Employing an experimental design, the effect of link colour on both performance and subjective measures was studied. Eighty-six undergraduates carried out an information retrieval task using two versions of the same intranet site. Analysis showed an effect of link colour both on accuracy and rated display quality, with blue links on a white background resulting in better outcomes than black links on a white background. Analysis of navigation behaviour showed that the home page was used more frequently than either the site map or the search function; however, use of these three navigation support functions was associated with poor and inefficient task performance. The results are discussed in terms of schema theory [Norman, D. A. (1988). The psychology of everyday things. Basic Books; Norman, D. A. (1999). Internetworking, 2(1)] and design recommendations are given.