OBJECTIVES: This study examined whether an online course would lead to increased knowledge about the medical issues volunteers encounter during a marathon. MATERIALS AND METHODS: Health care professionals who volunteered to provide medical coverage for an annual marathon were eligible for the study. Demographic information about medical volunteers including profession, specialty, education level and number of marathons they had volunteered for was collected. A 15-question test about the most commonly encountered medical issues was created by the authors and administered before and after the volunteers took the online educational course and compared to a pilot study the previous year. RESULTS: Seventy-four subjects completed the pre-test. Those who participated in the pilot study last year (N = 15) had pre-test scores that were an average of 2.4 points higher than those who did not (mean ranks: pilot study = 51.6 vs. non-pilot = 33.9, p = 0.004). Of the 74 subjects who completed the pre-test, 54 also completed the post-test. The overall post-pre mean score difference was 3.8 +/- 2.7 (t = 10.5 df = 53 p < 0.001). While subjects with all levels of volunteer experience demonstrated improvement, only change among first time marathon volunteers was significantly different from the others. Subjects reporting all degree/certification levels demonstrated improvement, but no difference in improvement was found between degree/certification levels. CONCLUSION: In this follow-up to the previous year's pilot study, online education demonstrated a long-term (one-year) increase in test scores. Testing also continued to show short-term improvement in post-course test scores, compared to pre-course test scores. In general, marathon medical volunteers who had no volunteer experience demonstrated greater improvement than those who had prior volunteer experience.