In this case we present a patient with unruptured non-coronary sinus of Valsalva aneurysm associated with diverse clinical findings, caused by acquired degenerative changes of the aortic wall. A previously healthy 36-year-old female was admitted to the neurological clinic of our hospital having suffered from an episode of unconsciousness prior to admission, with accompanying seizures. For the preceding two months she had also been suffering from dyspnoea and palpitation. Neurological examination, computed tomography of the head and electroencephalography were with normal findings. Thereafter, due to paroxysm of supraventricular tachycardia she was referred to cardiology clinic. On routine physical examination a diastolic murmur was detected and the patient was referred for transthoracic echocardiography. This examination revealed a large, unruptured noncoronary sinus of Valsalva aneurysm, which was thereafter confirmed by transoesophageal echocardiography a angiography. The patient was indicated for surgical correction with aortic valve and aortic root replacement by Bentall procedure. Histological examination of the part of resected aneurysm found cystic medial degeneration of the aortic wall, also called cystic medial necrosis.