•Mitral valve (MV) aneurysms are unusual lesions, its incidence is 0.02% to 0.29%.•Most cases of MV aneurysms are a complication of aortic valve endocarditis.•Direct Infection of MV leaflets and degenerative lesions could cause a MV aneurysms.•MV aneurysms are rarely surgical complication, however, it should be kept in mind.