PURPOSE: To evaluate the usefulness of 'bridging vascular sign' in the diagnosis of a subserosal/exophyticuterine leiomyoma and the helpfulness of this sign in the differentiation of a uterine leiomyoma from adnexalmasses on pelvic magnetic resonance (MR) imaging. MATERIALS AND METHODS: Of 20 women with a solitary pelvic massin whom pelvic MR imaging was performed during recent three years to differentiate a uterine leiomyoma from anadnexal mass, 12 with surgicopathologically proven subserosal/exophytic uterine leiomymas were included in thisstudy. The other eight women were proved to have tubo-ovarian abscess (n = 3), ovarian endometrioma (n = 2),ruptured corpus luteum cyst (n = 2), and ovarian fibroma (n = 1). A 1.5 T unit was used to obtain axial/sagittalT1- and T2-weighted and gadolinium-enhanced sagittal T1-weighted images. Positive 'bridging vascular sign' wasdefined through the retrospective review and analysis of MR findings as the presence of intervening curvilinear ortortuous signal-void vascular structures crossing the uterus and the pelvic mass. Using this sign in the diagnosisand differentiation of a uterine leiomyoma from adnexal masses, statistical significance was evaluated. RESULTS:'Bridging vascular sign' was present in eight of 12 leiomyomas, but no in adnexal masses. Using this sign in thediagnosis and differentiation of a uterine leiomyoma from adnexal masses, sensitivity was 66.7%, specificity 100%,positive predictive value 100%, negative predictive value 66.7%, and accuracy 80%. CONCLUSION: 'Vascular bridgingsign' on MR imaging may be a useful radiologic sign in the diagnosis and differentiation of a subserosal/exophyticuterine leiomyoma from adnexal masses.