PURPOSE: Phyllodes tumors of the breast are biphasic neoplasms. They are composed of epithelium and a spindle cell stroma. However, there is some controversy over its clinical behavior, pathologic characteristics, and local recurrence rates. Therefore we analyzed the clinicopathological characteristics of phyllodes tumor and the risk factor that influence a local recurrence after surgery were analyzed. METHODS: We retrospectively analyzed the medical records of 73 patients with a phyllodes tumor and who had undergone surgery at the Department of Surgery, Kosin University, from 1994 to 2005. The median follow up period was 73 months (range: 5-250 months). The microscopic slides were re-examined and the pathologic criteria we analyzed were cellular atypia, stromal cellularity, pleomorphism, necrosis, differentiation, the tumor margin, and the number of mitosis. The malignancy was reclassifed using the histological criteria reported by Pietruszka et at. (benign was 0-4 mitoses/10 highpower folds, borderline 5-9 mitoses, and malignant was more than 10 mitoses), The clinical features we evaluated included age, the preoperative diagnosis, the tumor size, surgical methods, and local recurrence. RESULTS: The mean age was 38.2 yr (range: 15-60 yr) and the mean tumor size was 4.3 cm (range: 1.6-18 cm), The most commonly performed surgical procedures were local or wide excision (60 cases, 82.2%), mastectomy in 10 cases (13.7%) and MRM in 3 cases (4.1%). Out of the 73 cases we reviewed, 49 (67.1%) were confirmed as being a benign, 3 (4.1%) were borderline, and 21 (28.7%) were malignant phyllodes tumor. Cellular atypia was minimal in 55 cases (75.3%) and it was prominent in 18 cases (24.6%). The stromal cellularity was minimal in 49 cases (67.1%) and it was prominent in 24 cases (32.8%). The tumor margin was infiltrating in 27 cases (36.9%) and pushing in 46 cases (63.0%). A local recurrence developed in 12 cases (16.4%). There were no dependable histopathological features to predict a local recurrence except for stromal cellularity, and an infiltrating margin. CONCLUSION: From the above results, the strong prognostic factors that can be used to predict a local recurrence appear to be stromal cellularity, and an infiltrating tumor margin.