<p class="abstract"><strong>Background:</strong> Headache is a common symptom. Correct diagnosis of the etiology is the key to successful treatment. Chronic headache are misdiagnosed as sinus headache because of presence of overlapping symptoms leading to unnecessary treatment with no relief to the patient. We decided to undertake this study with the objective of evaluating patients with chronic headache for presence of chronic rhinosinusitis and hence assess the contribution of sinus headache to chronic headache.</p><p class="abstract"><strong>Methods:</strong> The present study was conducted at Adichunchanagiri Institute of Medical Sciences, BG Nagara during the period January 2018 to December 2018. Patients presenting to OPD with chronic headache previously diagnosed as sinus headache were included in the study. A total of 174 patients were studied. All patients underwent detailed history taking, detailed ENT examination, and diagnostic nasal endoscopy. AAOHNS criteria for rhinosinusitis and IHS criteria for migraine and tension type headache were used for diagnosis. </p><p class="abstract"><strong>Results:</strong> We found that only 13% (n=23) cases had chronic rhinosinusitis and hence diagnosed as sinus headache. 53% (n=92) had migraine, 31% (n=54) had tension type headache and 3% (n=5) could not be categorized.</p><p class="abstract"><strong>Conclusions:</strong> Prevalence of sinus headache in our study was found to be 13%. There are high chances of misdiagnosing chronic headache as sinus headache because primary forms of headache can present with nasal symptoms. The AAOHNS criteria for rhinosinusitis and IHS criteria for migraine and tension type headaches are very useful and effective in making an accurate diagnosis.</p>