Behavioral training (BT) is recommended as a supplementary preventive treatment for migraine. Online interventions have been successful in promoting health behavior change, the evidence for online BT in migraine is limited, however. This randomized controlled trial aimed to determine the post-treatment effectiveness of online BT (n=195) compared to a waitlist control group (WLC; n=173) on migraine attack frequency (primary outcome), headache self-efficacy and locus of control (secondary outcomes). BT aims to counteract attacks in the prodromal stage through early detection of prodromal features and self-management via physical relaxation and cognitive behavioral regulation, and was offered with minimal e-mail support in eight online lessons. Results showed that 120 (62%) participants completed BT. A decrease of 20-25% in migraine attack frequency was found in both conditions without a between-group difference (ES=0.02, p= .71). BT participants improved more than WLC participants on migraine related self-efficacy (ES=0.86, p<.001), developed more internal (ES=0.57, p<.001), and less external control (ES=0.78, p<.001). To conclude, results at post-training did not corroborate that improvements in migraine attack frequency were due to online BT, the waitlist control group improved accordingly. However, positive effects of BT on self-efficacy and locus of control were established. We have to await the long term effects to see if improvements in psychological variables translate to a reduction in migraine headache. © 2014 Elsevier Ltd.