In spite of the enormous amount of research regarding classification, epidemiology, diagnosis, pathophysiology and treatment of migraines, aura, one of its hallmarks, stays much less studied. The objective of this study is, therefore, to evaluate the evolution of aura in patients submitted to placebo and three different drugs available in Brazilian public health units. We studied 86 patients during an acute migrainous attack, with aura at the moment of the evaluation. Patients were randomized to receive one of the following substances, in a parenteral route: placebo, dipyrone, chlorpromazine and magnesium sulphate. Magnesium sulphate was superior to placebo (p <0,05) 30 and 60 minutes after its administration. Dipyrone and chlorpromazine reduced the duration of the aura, when compared to placebo, 60 minutes following their administration. Our findings make possible some speculations about the pathophysiology of migraine, as well as about the therapeutic approach of patients presenting migrainous aura.