en Biostatistics and Epidemiology Biostatistics and Epidemiology Original Research Original Research <strong>Background: </strong>Coriandrum sativum (coriander) is prescribed as a treatment for headache in traditional Persian medicine. Several investigations have been carried out to find the medicinal properties of this plant. However, no study has evaluated the effectiveness of this plant on becoming migraine-free.<br> <strong>&nbsp;&nbsp; Methods: </strong>Sixty-eight migraineurs were randomly allocated to two equal groups of intervention and control. Each received 500 mg of<a name="OLE_LINK1"> sodium valproate</a> in addition to 15 mL of coriander or placebo syrup three times a day. We followed subjects and recorded their migraine duration in the 1^st, 2^nd, 3^rd, and 4^th weeks. We applied an appropriate statistical model so as to consider special features of the data, which led to more accurate results using SAS 9.4<br> <strong>&nbsp;&nbsp; Results:</strong> Our findings showed that the probability of being migraine-free was not only considerably higher in final weeks of the study (p<0.001) in all patients of the intervention group than placebo group, but it was also significantly higher in patients less than 30 years of age compared to patients older than 30 years old. Migraine duration in migraineurs using coriander syrup reduced considerably during the study (p<0.001).<br> <strong>&nbsp;&nbsp; Conclusion: </strong>The finding of this study revealed that coriander has a significant effect both on the probability of being migraine free and the duration of migraine attacks. Its effects were more significant during the final weeks of study.<br> &nbsp; Migraine headache, Coriandrum sativum, Herbal drug, Clinical trial, Mixture model 311 317 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-4333-1&slc_lang=en&sid=1 Samaneh Mansouri samaneh.mansoory@gmail.com 200319475328460063943 200319475328460063943 No Department of Biostatistics, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran Iraj Kazemi i_kazemi@yahoo.com 200319475328460063944 200319475328460063944 No Department of Statistics, Faculty of Sciences, University of Isfahan, Isfahan, Iran Ahmad Reza Baghestani baghestani@sbmu.ac.ir 200319475328460063945 200319475328460063945 Yes Physiotherapy Research Center, Department of Biostatistics, Faculty of Para-medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran Farid Zayeri zaerif38@gmail.com 200319475328460063946 200319475328460063946 No Department of Biostatistics, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran Zahra Ghorbanifar ghorbaniza14@gmail.com 200319475328460063947 200319475328460063947 No Persian Medicine Department, School of Medicine, AJA University of Medical Sciences, Tehran, Iran