-Background: Migraine is a chronic neurological disease with several trigger factors, including dietary, hormonal and environmental factors. Purpose: To analyse precipitating factors in a sample of migraine patients. Method: Two hundred consecutive migraine patients were interviewed about possible trigger factors for migraine attacks. Results: Most patients showed at least one dietary trigger, fasting was the most frequent one, followed by alcohol and chocolate. Hormonal factors appeared in 53% , being the pre-menstrual period the most frequent trigger. Physical activities caused migraine in 13%, sexual activities in 2.5% and 64% reported emotional stress a trigger factor. 81% related some sleep problem as a trigger factor. Regarding environmental factors, smells were reported by 36.5%. Conclusion: Trigger factors are frequent in migraine patients, its avoidance may decrease headache frequency and also improve patients' quality of life.KEY WORDS: migraine, trigger factors. fatores desencadeantes de enxaquecaResumo -Introdução: A enxaqueca é uma doença neurológica crônica que apresenta diversos desencadeantes como fatores alimentares, hormonais e ambientais. Objetivo: Analisar os fatores desencadeantes em uma amostra de pacientes com enxaqueca. Método: Duzentos pacientes com diagnóstico de enxaqueca foram questionados sobre fatores que pudessem desencadear suas crises. Resultados: 83,5% apresentaram algum fator alimentar, jejum foi o fator mais freqüente, seguido de álcool e chocolate. Dos fatores hormonais, o período pré-menstrual foi o mais freqüente. Atividade física causou enxaquecas em 13%, atividade sexual em 2,5%, estresse em 64% e 81% relataram o sono como fator desencadeante. Em relação aos fatores ambientais, odores foram desencadeantes em 36,5%. Conclusão: Os fatores desencadeantes são freqüentes em enxaqueca e a sua detecção deve ser pormenorizada para que se reduza a freqüência de crises e melhore a qualidade de vida do paciente.PAlAvRAS-cHAvE: enxaqueca, fatores desencadeantes. Migraine is a chronic debilitating neurological condition with several trigger factors. It usually begins in childhood or adolescence and can remain with the patient for the whole life. It is more common in women than men, its prevalence is 12% of the general population, affecting 18% to 20% of women, occurring mainly during their productive and reproductive phases (20 to 50 years old). Therefore, migraine has a significant socioeconomic impact and in patients quality of life 1 . Migraine is a complex disorder with several pathopsysiological mechanisms involved, such as hypothalamic dysfunction shown by a chronobiologic dysregulation, and a possible hyperdopaminergic state 2 . A variety of external and internal factors have been demonstrated to precipitate migraine attacks.Trigger factors are important in migraine management since their avoidance may result in a better control of the disorder. Several studies are consistent with stress, lack of sleep, and fasting being the most common trigger factors 3,4 , but some o...