<p>Abstract</p> <p>Background</p> <p>Previous research has shown that internet education can lead to short-term improvements in clinicians' knowledge, confidence and communication practices. We wished to better understand the duration of these improvements and whether different curriculum delivery strategies differed in affecting these improvements.</p> <p>Methods</p> <p>As previously described, we conducted a randomized control trial comparing four different strategies for delivering an e-curriculum about herbs and other dietary supplements (HDS) to clinicians. The four strategies were delivering the curriculum by: a) email over 10 weeks; b) email within one week; c) web-site over 10 weeks; d) web-site within one week. Participants were surveyed at baseline, immediately after the course and 6–10 months after completing the course (long-term). Long-term outcomes focused on clinicians' knowledge, confidence and communication practices.</p> <p>Results</p> <p>Of the 780 clinicians who completed the course, 385 (49%) completed the long-term survey. Completers and non-completers of the long-term survey had similar demographics and professional characteristics at baseline. There were statistically significant improvements from baseline to long-term follow-up in knowledge, confidence and communication practices; these improvements did not differ by curriculum delivery strategy. Knowledge scores improved from 67.7 ± 10.3 at baseline to 78.8 ± 12.3 at long-term follow-up (P < 0.001). Confidence scores improved from 53.7 ± 17.8 at baseline to 66.9 ± 12.0 at long term follow-up (P < 0.001); communication scores improved from 2.6 ± 1.9 at baseline to 3.6 ± 2.1 (P < 0.001) at long-term follow-up.</p> <p>Conclusion</p> <p>This e- curriculum led to significant and sustained improvements in clinicians' expertise about HDS regardless of the delivery strategy. Future studies should compare the impact of required vs. elective courses and self-reported vs. objective measures of behavior change.</p>