['This study was designed to examine the change in mean platelet volume (MPV) over the course of infective endocarditis (IE) and also the association between MPV and complications including embolic events in IE.', "Forty patients (26 male, mean age 46±15 years) who were hospitalized with a diagnosis of IE at the Department of Cardiology, Erciyes University, from March 2005 to August 2008, were retrospectively evaluated. The diagnosis of IE was made clinically and was confirmed with Duke's criteria. The erythrocyte sedimentation rate (ESR), high-sensitivity C-reactive protein (hs-CRP), and MPV were measured before treatment and periodically during the follow-up period, until discharge.", 'There were 27 cases of native valve endocarditis and 13 of prosthetic valve endocarditis. While 31 patients were treated medically, an operation was performed in nine patients because of unsuccessful medical therapy. On admission, mean MPV was 10.8±1.1 fl, ESR was 82±26mm/h, and hs-CRP was 110±72mg/l. Seven patients died: one intraoperatively, three patients postoperatively, and three patients during medical treatment. With the exception of these seven patients, ESR and hs-CRP were significantly reduced in all patients at discharge compared to levels at hospitalization (ESR 82±26 to 32±22, p=0.001 and hs-CRP 110±72 to 25±15, p=0.001). Similarly, we detected a significant decrease in MPV from hospitalization to discharge, i.e., from the active period of the disease to recovery (10.8±1.1 to 9.7±0.8 fl, p=0.002). In addition, MPV was found to be significantly higher in patients with observed embolic complications (11.5 vs. 10.3 fl, p=0.001), other complications (11.0 vs. 10.2 fl, p=0.001), and death (11.1 vs. 10.4 fl, p=0.005).'] Does mean platelet volume predict embolic complications and prognosis in infective endocarditis?