['To develop and evaluate the efficacy of an online continuing education course for professionals who provide food safety information to high-risk populations.', 'A 2-credit graduate-level class was converted into six web-based modules (overview of foodborne illness, immunology, pregnancy, human immunodeficiency virus, cancer and transplants, and lifecycle) and offered to nutrition and health professionals. Participants had 8 weeks to complete the modules, pre and post questionnaires, and course evaluation. Those who successfully completed the protocol received six continuing education units from one of three professional associations. Change in knowledge was measured using pre and post questionnaires. Course efficacy was evaluated using a post-course questionnaire.', 'A convenience sample of 140 registered dietitians/dietetic technicians registered, nurses, and extension educators were recruited through professional conferences and electronic mailing lists to take the course.', 'Analysis of variance was used to evaluate differences in knowledge scores for all groups across five main effects (attempt, module, profession, age, and education). Course evaluation responses were used to assess course effectiveness.', 'For each module, knowledge scores increased significantly (P<0.001) from pre to post questionnaire. Overall, knowledge scores increased from 67.3% before the modules to 91.9% afterwards. Course evaluation responses were favorable, and participants indicated that course objectives were met.'] Does online continuing education course enhance nutrition and health professionals ' knowledge of food safety issues of high-risk populations?