Intravenous leiomyomatosis is a rare variant of leiomyoma that could result in death. Early and accurate diagnosis and appropriate treatment strategies play a dominant role in good prognosis. Eighteen cases of Intravenous leiomyomatosis , along with clinicopathologic data, were retrieved from our database. Most of the patients who ranged in age from 33 to 54 years (median, 44 years) presented with a pelvic mass or abnormal uterine bleeding. The diagnosis was confirmed by a immunohistochemical staining for smooth muscle actin, CD34, and Ki67. Surgical exploration confirmed the presence of a uterine mass (mean size, 5.08 cm). Wormlike plugs were identified within the broad ligament in 5 cases. The tumor penetrated to the inferior vena cava in 1 case. Histologic variants were noted in 33.33% (6/18) of our cases, which were classified as cellular intravenous leiomyomatosis (3 cases) and intravenous leiomyomatosis with papillary-like contour (1 case) and with fat metaplasia (2 cases). The 18 cases are made up 0.097% of all genital smooth muscle tumor cases of the hospital. The ratios of intravenous leiomyomatosis with uterine leiomyoma, with adenomyosis, with uterine leiomyoma and adenomyosis were 38.89% (7/18), 11.11% (2/18), and 27.78% (5/18), respectively. Follow-up information was available for 16 patients, with a follow-up duration of 26 to 104 months (mean, 55 months). Three cases (16.67%) recurred in patients younger than 40 years (33, 34, and 37 years). We propose that young patients undertake hysterectomy and unilateral salpingo-oophorectomy if they do not have any birthing requests. The cases of intravenous leiomyomatosis were underestimated because early diagnosis was easily missed. It is important to adequately sample all uterine leiomyomas and carefully examine the soft tissue on either side of the lower uterine segment below the peritoneal reflection to identify early-stage intravenous leiomyomatosis. Copyright © 2011 Elsevier Inc. All rights reserved.