The aim of this study was to evaluate and define the triggers of the acute migraine attack. Patients rated triggers on a 0–3 scale for the average headache. Demographics, prodrome, aura, headache characteristics, postdrome, medication responsiveness, acute and chronic disability, sleep characteristics and social and personal characteristics were also recorded. One thousand two hundred and seven International Classification of Headache Disorders-2 (1.1–1.2, and 1.5.1) patients were evaluated, of whom 75.9% reported triggers (40.4% infrequently, 26.7% frequently and 8.8% very frequently). The trigger frequencies were stress (79.7%), hormones in women (65.1%), not eating (57.3%), weather (53.2%), sleep disturbance (49.8%), perfume or odour (43.7%), neck pain (38.4%), light(s) (38.1%), alcohol (37.8%), smoke (35.7%), sleeping late (32.0%), heat (30.3%), food (26.9%), exercise (22.1%) and sexual activity (5.2%). Triggers were more likely to be associated with a more florid acute migraine attack. Differences were seen between women and men, aura and no aura, episodic and chronic migraine, and between migraine and probable migraine.