Since the web is always developing, and users' needs are constantly changing, organisations in recent decades have increasingly focused on developing information and communication technologies (ICTs). To introduce new e-services to their customers, they have largely invested in web development and promotional activities. The present study, therefore, describes a novel approach for evaluating and improving website link structure by using web usage mining, as well as assessing the usage pattern of an Iranian organisation. Analysing this pattern, the visited paths are illustrated and the website is modelled as a directed graph. On the basis of graph theory definitions, some measures are introduced and applied to evaluate website usability and link structures. Finally, a ranking improvement strategy is proposed and findings are discussed.