Clozapine is an antipsychotic medication used to control the symptoms of schizophrenia. Due to the frequent occurrence of adverse effects, it is reserved for patients meeting the criteria of treatment-resistant schizophrenia. Among the less typical side effects of clozapine are asymptomatic eosinophilia and eosinophilic inflammation of organs such as the myocardium, as well as vasculitis, which most commonly affects small vessels in the skin. We present the case of a 54-year-old woman with treatment-resistant paranoid schizophrenia, who developed aortitis accompanied by eosinophilia as an adverse reaction to clozapine therapy. Symptoms resolved after discontinuation of the medication. The patient gave written consent for the publication of her medical case and treatment course. Inflammatory changes in large vessels such as the aorta during clozapine treatment have not been described in the literature. The coexisting eosinophilia suggests an eosinophilic nature of the inflammatory changes within the aortic wall. The presented case aims to raise awareness about possible atypical complications of the treatment and to expedite their diagnosis, which may prevent permanent negative health consequences in patients.