Transesophageal echocardiography is a new diagnostic method for visualization of retrocardial structures and heart valves with high resolution. This retrospective analysis describes the use of and the findings by transesophageal echocardiography in patients suspected to suffer from endocarditis studied in three hospitals. 50 patients were studied; the diagnosis was confirmed in 64%, whereas 36% (controls) had other findings. The leading initial symptoms were fever and valvular incompetence. Laboratory parameters were altered in both groups with equal frequency. One or more diagnostic features were detected by transesophageal echocardiography in 88% of patients with endocarditis: vegetations (approximately with equal frequency on the mitral and the aortic, rarely on the tricuspid valve) were detected in 75% and/or abscesses in 22% of them. Only one patient in the control group with a history of endocarditis had vegetation-like structures on the aortic valve. Transesophageal echocardiography was on the average performed on the seventh day of hospitalization. With the exception of one female patient, all had been treated with antibiotics. Valve replacement was recommended in 65% of the patients with endocarditis and was in 59% also performed (single or double valve replacement), most frequently because of aortic or mitral regurgitation. The other patients were treated with antibiotics. Transesophageal echocardiography thus detects vegetations and abscesses in endocarditis frequently, findings that influence treatment in a significant manner.