The aim of this study was to assess the predictive value of spontaneous echocardiographic contrast (SEC) detected in the thoracic aorta by transesophageal echocardiography (TEE) on intermediate-term cardiovascular morbidity and mortality. We studied 299 consecutive patients (aged 61 ± 13 years) without aortic aneurysm or dissection, who underwent TEE in 1995 to 1996. Cardiovascular deaths and nonfatal events were recorded over a period of ≤60 months. Left ventricular function was classified as preserved versus depressed according to ejection fraction values (>40% vs ≤40%) on 2-dimensional echocardiography. SEC was identified in 35 patients (11.7%). During follow-up, 66 patients died (36 deaths were due to cardiovascular causes; 10 and 26 cardiovascular deaths occurred in patients with and without SEC, respectively [p <0.001]). Survival time was significantly reduced in patients with versus without SEC (28 ± 18 vs 39 ± 19 months, p = 0.0012). Multivariate analysis revealed that the presence of SEC doubled the odds for cardiovascular death and for the combined end point of cardiovascular death and events. There was a significant difference in survival distributions between patients with and without SEC between both genders (p <0.001). In patients with normal or mildly reduced left ventricular function, SEC was predictive of an adverse outcome, whereas this was not the case in patients with more severely depressed cardiac function. It is concluded that the presence of SEC in the thoracic aorta is associated with a high risk of cardiovascular events and/or death over intermediate-term follow-up.