The natural history of patients with coronary artery disease and diastolic dysfunction who underwent coronary artery bypass grafting (CABG) is not well known. The aims of our study were to evaluate the incidence of diastolic dysfunction, its evolution after CABG and its possible correlation with adverse in-ICU prognosis. We studied 88 consecutive patients scheduled for CABG with not severely depressed left ventricular function (ejection fraction > 35%) and multivessels disease. Buckberg cardioplegia was used for myocardial protection. Diastolic function was investigated by recording mitral and venous pulmonary flow by transesophageal Doppler echocardiography (TEE). TEE examination was performed in operative room pre and post-bypass, at ICU arrival and after three months. Diastolic dysfunction was defined as mild, moderate and severe. Adverse in ICU events were defined as: use of inotropic drugs or ventricular mechanical support, an ICU stay > 24 hours, perioperative myocardial infarction and death. The study group was compared with a control group. T-Student test was used; a p < 0.05 was considered significant. A reduced diastolic function was present in 77% of patients at baseline examination. Diastolic dysfunction did not worsen significantly after hypothermic cardiac arrest and reperfusion. It persisted during ICU stay and normalized after three months from CABG in the majority of patients (85%). Diastolic failure was not associated with an adverse ICU prognosis (adverse events: 18 versus 13%; p = ns).