Thirty-four cases of phyllodes tumor of the breast were studied to evaluate the clinical and pathological features, which correlate with local recurrence. Histologically, local recurrence correlated with the finding of more than ten mitotic figures per ten high-power fields, marked cellularity, prominent nuclear pleomorphism, and stromal overgrowth. Older patients and patients with larger tumors had a higher probability of local recurrence. Stromal overgrowth correlated with the other histological parameters, with rapid tumor growth, a tumor diameter of over 10 cm, and with local recurrence. It was thus considered to be a histological indicator of the malignant potential of phyllodes tumor of the breast.