Diastole begins with closure of the semilunar valves and is divided into four phases: isovolumic relaxation , rapid filling, diastasis (passive filling) and atrial systol. Assessment of diastolic functions have inportance, because in various heart diseases, diastolic functions may be impaired before the systolic fuııctions and cause of the symptoms . In this article, we present physiology of diastole, causes of diastolic dysfunction and evaluation of diastolic functions by echocardiography.