BACKGROUND:We performed a post hoc, subgroup analysis of a phase 3, randomized, double-blind, placebo-controlled study of erenumab for prevention of episodic migraine (STRIVE) to determine the efficacy and safety of erenumab in women with self-reported menstrual migraine. METHODS:Patients received placebo, erenumab 70 mg, or erenumab 140 mg subcutaneously once monthly during the 6-month double-blind treatment phase of STRIVE. Women who reported history of menstrual migraine and who were ≤ 50 years old were included in the analysis. Endpoints were change from baseline in monthly migraine days (MMD) and monthly acute migraine-specific medication days (MSMD; among patients who took acute migraine-specific medications at baseline), proportion of patients achieving ≥ 50% reduction from baseline in MMD, and incidence of adverse events. RESULTS:Among 814 women enrolled in STRIVE, 232 (28.5%) reported a history of menstrual migraine and were ≤ 50 years old. Of the 232 patients, 214 (92%) had a baseline MMD > 5, suggesting a high proportion of women with attacks outside of the 5-day perimenstrual window (2 days before and 3 days after the start of menstruation). Information on "migraine days" includes (and does not discriminate between) perimenstrual and intermenstrual migraine attacks. Between-group differences from placebo over months 4-6 for erenumab 70 mg and 140 mg were - 1.8 (P = 0.001) and - 2.1 (P < 0.001) days for MMD and - 1.6 (P = 0.002) and - 2.4 (P < 0.001) days for acute MSMD, respectively. The odds of having a ≥ 50% reduction from baseline in MMD over months 4-6 were 2.2 (P = 0.024) and 2.8 (P = 0.002) times greater for erenumab 70 mg and 140 mg, respectively, than for placebo. Erenumab had an overall safety profile comparable to placebo. CONCLUSION:Data from this subgroup analysis of women with menstrual migraine are consistent with data from the overall STRIVE episodic migraine population, supporting the efficacy and safety of erenumab in women who experience menstrual migraine. TRIAL REGISTRATION:ClinicalTrials.gov, NCT02456740. Registered 28 May 2015.