OBJECTIVES Evidence on repeating vaccination misinformation or "myths" in debunking text is inconclusive; repeating myths may unintentionally increase agreement with myths or help discredit myths. In this study we aimed to compare the effect of repeating vaccination myths and other text-based debunking strategies on parents’ agreement with myths and their intention to vaccinate their children. METHODS For this online experiment we recruited 788 parents of children aged 0 to 5 years; 454 (58%) completed the study. We compared 3 text-based debunking strategies (repeating myths, posing questions, or making factual statements) and a control. We measured changes in agreement with myths and intention to vaccinate immediately after the intervention and at least 1 week later. The primary analysis compared the change in agreement with vaccination myths from baseline, between groups, at each time point after the intervention. RESULTS There was no evidence that repeating myths increased agreement with myths compared with the other debunking strategies or the control. Posing questions significantly decreased agreement with myths immediately after the intervention compared with the control (difference: −0.30 points, 99.17% confidence interval: −0.58 to −0.02, P = .004, d = 0.39). There was no evidence of a difference between other debunking strategies or the control at either time point, or on intention to vaccinate. CONCLUSIONS Debunking strategies that repeat vaccination myths do not appear to be inferior to strategies that do not repeat myths.