Background <p>Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare, multisystemic, immune-mediated inflammatory disease. Carotid artery dissections involving both the cervical internal carotid artery and common carotid artery are rare. To our knowledge, there are no previous reports of cervical carotid artery dissections associated with EGPA. This is the first report of spontaneous cervical artery dissection involving the common and internal carotid arteries associated with EGPA.</p> Case presentation <p>A 64-year-old woman with a history of EGPA presented with Horner syndrome. She was receiving glucocorticoids for EGPA and anticoagulation therapy for atrial fibrillation. Ultrasonography demonstrated an intimal flap and double lumen within the common carotid artery and internal carotid artery. The patient was followed up with continued medications. No ischemic stroke occurred, and Horner syndrome had improved at 6 month visit after onset. Ultrasonography showed no recurrence or aneurysm formation, but complete resolution of carotid artery dissections has not yet been confirmed.</p> Conclusions <p>This case suggests a possible association between EGPA and carotid artery dissections. In such cases, an underlying disease involving endothelial dysfunction should be investigated. Clinicians should consider underlying systemic vasculitis such as EGPA in cases of atypical or extensive cervical artery dissections.</p>