Physician knowledge of the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) guidelines is unknown and may contribute to the prevalence of uncontrolled hypertension. Our objective was to determine physician knowledge of JNC 7 guidelines and whether online instruction could improve knowledge. A pretest served as baseline knowledge, and comparison with a post-test after completing an online didactic demonstrated improvement in knowledge. Participants included 1280 physicians at 45 internal medicine residency training programs. Average baseline knowledge of six concepts of hypertension was 51.2%. Attending physicians performed better than trainees on some but not all concepts (p<0.05). Third-year post-graduate trainees performed better than first-year trainees on some but not all concepts (p<0.05). Knowledge increased significantly on all concepts after completing the curriculum (p<0.05). The authors demonstrated that physician knowledge of JNC 7 guidelines is poor but can be improved by an online curriculum. Further study is needed to determine the impact of physician education on clinical outcomes in individuals with hypertension.