Underdiagnosis of primary headaches was evaluated in 504 patients attending six Headache Centres in Lombardy. We found high figures of missed diagnoses (no diagnosis of a specific headache form), and of misdiagnosis (non-concordance between previous diagnoses made by the GP and the final diagnoses given by the headache specialist). We note that underdiagnosis in headache patients may have negative consequences, enhancing the risk of progressive worsening of primary headache syndromes, increasing their impact on individuals and on society, and favouring medication overuse.