Intravenous leiomyomatosis is characterized by a proliferation of benign smooth muscular tissue growing into uterine with malignant appearance. On extremely rare occasions, the tumor may grow out of the pelvis and extend into the inferior vena cava and the right atrium. We report a case of intravenous leiomyomatosis extending into the right atrium. A 41-year-old woman complained of 20 days of intermittent abdominal pain and lower limbs swell. Medical history of the patient revealed a previous hysterectomy operation 3 years ago due to uterine leiomyoma. Echocardiography showed a homogenous mass extending from the inferior vena cava to the right atrium, without evidence of adherence to the right atrial wall, the left ventricular ejection fraction was only 60%. Computer tomography showed that a large mass arising from the left internal iliac vein and extending into the right chambers. Pelvic vascular ultrasound revealed the thrombotic material in the inferior vena cava and the left common iliac vein, and confirmed the presence of a complex mass in the left annex region. Based on the findings, the initial diagnosis was intracardiac and intravenous tumor. An operation was performed through a sternotomy and laparotomy to remove the whole tumor from the left common iliac vein to the right atrium, ligate left internal iliac vein mean-wile. No hormonal therapy was administrated after the operation. Immunohistochemical studies revealed that the tumor cells were fusiform shape, there was no karyokinesis and necrosis, and the tumor cells were positive for smooth muscle antigen and desmin, as well as estrogen receptor and progesterone receptor. Six months postoperation follow-up revealed no signs of recurrence. The differential diagnosis of the disease compared with primary cardiovascular sarcomas and thrombus was difficult. The final diagnosis relied on immunohistochemical analysis, however, the short-term result of operation was acceptable.