The clinical and echocardiographic findings of four patients with right ventricular tumors (three myxomas and one metastatic melanoma) are presented. All four patients previously had been evaluated by competent cardiologists, and the diagnosis of a right ventricular tumor was missed. The initial echocardiograms were interpreted as not showing any right ventricular tumor; but on review we found that the correct diagnosis could have been made. The presence of the right ventricular myxomas was confirmed at angiography and surgery. However, the attachment of the stalk of the mycoma could not be determined confidently by angiography alone, and in two of the three cases two-dimensional echocardiography was required to identify correctly the location of the base of the stalk. This paper emphasizes the usefulness and technical difficulties of M-mode and two-dimensional echocardiography in the diagnosis of a right ventricular tumor.