This study presents an empirical investigation of online hierarchical repositories of items presented to university students in Web-supported course websites, using Web mining methods. To this end, data from 1747 courses were collected, and the use of online repositories of content items in these courses was examined. At a later stage, courses with a significant repository size (15 files or more) were analyzed using clustering algorithms in order to reveal hierarchical structures and to identify associations between these structures and course characteristics. Results suggest five types of structures and some statistically significant differences between them regarding the researched variables. A discussion of these results is provided below. (Contains 1 figure and 6 tables.)