We previously reported on the efficacy of transcervical needle biopsy of a uterine muscle tumor. In this study, to examine diagnostic accuracy of our needle biopsy with small specimen size, previous slide preparations were used from 8 cases diagnosed with leiomyosarcoma and from 24 post-operative leiomyoma cases. Each tissue specimen was examined through needle biopsy-sized slit that had been randomly positioned over the slide. Three predictors: mitotic index, cytologic atypism, and tumor cell necrosis were evaluated on a 3-point scale (0, 1, or 2 points). When the diagnostic cut-off value was set to two, the sensitivity was 92.5% and the specificity was 100%.