The echocardiographic findings of two unusual cases of malignant uterine tumors that invaded the heart are reported. A woman previously operated on for invasive cervical carcinoma had multiple embolic phenomena and evidence of obstruction to mitral flow. An echocardiogram showed a mass in the left atrium that reached the mitral valve ring. The tumor was implanted in a pulmonary vein and was removed with no complications. Cell type indicated metastatic carcinoma of the cervix. In the second case the patient had a large abdominal mass and precordial manifestations of obstruction and regurgitation of the tricuspid valve. An echocardiogram showed that a mass emanating from the inferior vena cava filled the right atrium and part of the right ventricle. The trajectory of the tumor was followed to its origin in an ovarian vein by tomography. The entire tumor was removed and identified as endometrial stromal sarcoma. An increase in operations with or without radiation therapy for malignant tumors has augmented the frequency of metastatic invasion of the heart; intracavitary extension tends to results from embolization or propagation along great veins. This is the first report of a uterine carcinoma reaching the heart by way of the pulmonary veins and of invasion of the heart by endometrial stromal sarcoma, both with successful excision.