We report the magnetic resonance imaging findings of a case of vaginal leiomyosarcoma. The lesion was demonstrated as a well-defined heterogeneously hyperintense mass within the vagina on T2-weighted images and was demonstrated as a hypointense mass on T1-weighted images. The mass showed irregular enhancement on fat-suppressed T1-weighted images after administration of gadopentate dimeglumine. On pathological specimen, the nonenhancing foci of the mass were seen as the necrotic portion of the lesion.