Introduction: Diagnosis of primary headaches is based upon clinical symptoms. However, our knowledge regarding biochemical correlation of their symptoms is limited. This study tries to find out whether symptoms during migraine have any association with inter-ictal plasma CGRP concentration. Methods: Fifty migraineurs were included after screening for inclusion and exclusion criteria for this study. Their clinical history was taken in detail and recorded in a semi-structured performa. Blood was drawn from ante-cubital vein (at least after three days of last headache) and separated plasma was stored at -70C. CGRP was analysed with commercially available ELISA kit. Data was analyzed with the help of SPSS V11.0 for Windows. Chi-Square test, independent sample t test, one way ANOVA and multivariate regression analysis was used for statistical analysis. Results: Age of subjects (P=0.02), total duration of illness (P=0.04) and frequency of migraine episode per month (P=0.03) had significant association with inter-episodic plasma CGRP concentration. Other headache characteristics were not related to the plasma CGRP concentration except cranial  autonomic symptoms where higher level was noticed in subjects with bilateral cranial autonomic symptoms with lateralized severity (F = 4.59; P=0.01). Conclusion: Laterality of cranial autonomic symptoms influences the inter-ictal plasma CGRP concentration in migraineurs.

Key Words: Migraine, cranial autonomic symptoms, CGRP, Inter-ictal period