Abstract. Objectives: To test the hypothesis that integration of the EMCyberSchool, a computer-assisted instruction (CAI) tool available on the Internet, into the curriculum of a senior medical student subinternship in emergency medicine (EM) would improve exam scores and course satisfaction. Methods: Students were prospectively randomized, by four-week blocks, into a CAI group and a no-CAI group. All students were surveyed on previous computer experience and their use and opinion of the EMCyberSchool. Results: Completed data were obtained from 100 of 120 students. Sixty-five percent of the students said they wanted CAI as an adjunct to their course curricula; only 28% actually used the educational tool. The students who used the site rated it useful (4.2/5), easy to use (4.4/5), and easy to access (4.1/5). Of the students who had access, and chose not to use the EMCyberSchool, 77.8% reported not having enough time as the reason for not using the site. The mean exam scores were 72.8% for the students in the CAI group and 68.2% for those in the no-CAI group (p = 0.058). In the CAI group, 77.5% (31/40) of the students rated the course as outstanding or excellent; compared with 66% (33/50) in the no-CAI group (p = 0.23). Conclusions: Although desired, it remains unclear whether CAI on the Internet is a useful adjunct for teaching EM to medical students.