Purpose: Gonadotropin-releasing hormone(GnRH) analogues have been used as a conservative or preoperative ativetherapy in the treatment of uterine leiomyoma. Since these drugs, which can induce a low estrogenic state, affectonly undegenerative leiomyoma tissue, the aim of the present study was to differentiate degenerative leiomyomafrom undegenerative one by Gd-DTPA enhanced magnetic resonance imaging(MRI). Materials and Methods: There were 40masses in 24 patients; all were diagnosed by surgical-pathology. With superconductive 0.5T MR circuit, T1- andT2-weighted images and Gd-DTPA T1-weighted images were obtained. Based on a combination of signal intensities ofT2-weighted and enhanced T1 weighted image on the same tumor section all the lesions were classified to one offour MRI patterns. Pattern I was a heterogeneous hyperintensity on the T2-weighted images that was enhancement byGd-DTPA. Pattern II was a high signal intensity on the T2-weighted MR images but no enhancement by Gd-DTPA.Pattern III was a low to intermediate signal intensity on the T2-weighted MR images and enhancement on the Gd-DTPAT1-weighted images. Pattern IV was defined to a low to intermediate signal intensity on the T2-weighted images andno enhancement by Gd-DTPA. Each of these 4 groups of MRI pattern were co- rrelated to the surgical-pathologyfindings. Results: Pathologically, pattern I corresponded to an edematous leiomyoma in 3 cases and a connectivetissue leiomyoma in one case. Pattern II corresponded to three red degeneration, two cystic degeneration and oneinfected leiomyoma. Pattern III corresponded to eighteen undegenerative leiomyomas, but some of them showed focalconnective tissue proliferation. All of twelve cases in pattern IV corresponded to a hyaline degeneration.Conclusion: MRI with Gd-DTPA enhancement may differentiate undegenerative leiomyoma from degenerated one.