Swinburne University of Technology has experienced tremendous growth in open access online learning and as such is typical of the many Australian institutions that have ventured into online tertiary education. While research in online education continues to expand, comparatively little investigates students' enrolment and attrition. This research examines commencing enrolment and associated student withdrawal data, as well as performance scores from eight units forming a Marketing Major for an open access online undergraduate degree. Since data were collected over a five year period, trends and patterns within a substantial online undergraduate program can be explored. The paper discusses the challenges of analysing enrolment data. Initial findings suggest that retention strategies should be designed according to the stage students are at in their studies. Furthermore, the research informs the prioritisation and development of more effective enrolment and performance data reporting capabilities, which in turn would benefit student management and retention.