Little is known about how online learning may be used to disseminate health information rapidly and widely to large university populations if there is an infectious disease outbreak. During the SARS outbreak in Singapore in 2003, a six-lesson elearning module on SARS was developed for a large university population of 32,000 students. The module was developed within 2 months by 12 academic staff from medicine, economics, basic science, health promotion, microbiology, epidemiology and public health with support from 2 IT experts and 2 support staff. To ensure coverage of the entire student population, all students were required to complete the module within 9 months of its implementation to fulfill the graduation requirement. About 5,000 (16%) students read the module within the first month and almost all (96%) within 9 months of its implementation. The majority (86%) of the students who took the module for credits passed the module. Using this online format, health information was disseminated rapidly and efficiently to all university students during the SARS outbreak. This module could be adapted to other institutions with Internet support to disseminate timely health messages efficiently should an infectious disease outbreak occur. (Contains 1 table and 5 figures.)