Phyllodes tumor(PT) is a rare distinctive fibroepithelial breast tumor that occasionally shows unpredictable clinical behavior. Wide excision should be the primary treatment of PT and enucleation, the standard procedure for fibroadenoma(FA), is proscribed due to high frequency of local recurrence. Therefore an accurate preoperative diagnosis of PT is essential in order to ensure proper surgical treatment. However, the differentiation between benign PT and FA is often difficult on the basis of cytologic findings. In an attempt to better understand the cytologic features of benign PT and possibly to differentiate PT from FA on the findings of fine needle aspiration(FNA) smears, we reviewed cytologic smears from 22 histologically diagnosed cases each of benign PT and FA, respectively. The cytologic features assessed were cellularity and atypia of both epithelial and stromal components, and shape of epithelial cell clusters. Atypia of stromal cells was more frequent in PT, while blunt branching pattern of epithelial cells was more frequent in FA. The specific cytologic diagnosis of PT is not possible in many cases, but the abundance of stromal cells with moderate nuclear atypia in the correct clinical setting such as older age and larger size(>4cm) allows the diagnosis.