To evaluate the onset, magnitude and persistence of efficacy of remote electrical neuromodulation (REN) compared with placebo for the preventive treatment of migraine. Analysis was conducted on data from a prospective, double-blind, placebo-controlled clinical trial, which assessed the efficacy of REN for the prevention of migraine. The number of monthly migraine days (MMD) per group was calculated in 2-week intervals and compared between the groups. Differences between the active (N = 95) and placebo (N = 84) groups reached significance at 2 weeks: therapeutic gain 0.84 MMD, p = 0.036. Four weeks gain 1.59 MMD; p = 0.025, 6 weeks gain 2.27 MMD; p < 0.001, 8 weeks gain 2.68 MMD; p < 0.001. REN provides rapid and consistent efficacy in preventive treatment of migraine.