Background: Neurologic literature on therapeutic effect of subcutaneous corticosteroids in patients with migrainous chronic daily headache is scarce. The aim of this research is to assess the therapeutic effects of this management in such patients.Methods: Consecutive patients with migrainous chronic daily headache enrolled a prospective before-after therapeutic study during 2010-2013. Methylprednisolone 40 mg was divided into four subcutaneous injection doses. Two injections were administered in the right and left suboccipital area (exactly at retromastoid cervicocranial junction) and the other two injections in the lower medial frontal area (exactly at medial right and left eyebrows). A daily headache diary was filled out by the patients before and one month after the intervention. The severity of pain was classified based on a pain intensity instrument using numeric rating scale from 0-10 point scale. Paired t-test and Chi-square test were used for statistical analysis.Results: 504 patients (378 females, 126 males) with migrainous chronic daily headache were enrolled in the study. Dramatic, significant, moderate, mild, or no improvements respectively constituted 28.6%, 33.3%, 23.8%, and 14.3% of the post treatment courses. Therapeutic effect of intervention on mean pain scores was significant; t=7.38, df=20, P=0.000. Two cases developed subcutaneous fat atrophy in frontal injection site and three cases experienced syncope during injection.Conclusion: Subcutaneous corticosteroids could be used as an adjunct therapy in patients with migrainous chronic daily headache.