Cogan syndrome is an autoimmune disorder characterized with ocular and vestibular symptoms and only minority (less than 15%) of patients suffer from systemic disease which is explained by autoimmuune vasculitis.Cardiovascular involvement of Cogan syndrome is rare and  effects mostly subclavian and carotid arteries, aortic valve or aorta.Mitral valve involvement is rare. Below, we report a case with mitral valve involvement and Cogan syndrome. 39 year old male patient had admitted to our hospital with shortness of breath. He had history of previous aortic valve implantation in 2012. His transthorasic echocardiography demonstrated massively thickened mitral leaflets as well as moderate to severe mitral regurgitation.Transoesaphageal echocardiography revealed moderate to severe mitral regurgitation, severe thickening in both mitral leaflets and and mild restriction in leaflet motions.. Surgery was decided in case progressive dyspnea develops. Cogan syndrome is a vasculitis which effects medium sized arteries and aortic valve. Mitral valve involvement is rare. Differential diagnoses , as well as using certain medical treatments and rheumatic valve disease, were ruled out. This case is one of the rare examples of Cogan syndrome with mitral valve thickening.