Objective: Conventionally growth pattern, stromal overgrowth, stromal cellularity, stromal mitotic activity are the main parameters in grading of phyllodes tumors. Recent studies revealed that P53 and Ki67 expressions are both correlated with grade of phyllodes tumors of the breast. Method: We searched for p53 and Ki67 expression rates of benign and malignant phyllodes tumors in our archival data and correlated them with conventional parameters such as stromal cellularity and mitotic activity rates. 17 benign, 9 malignant phyllodes tumors were reevaluated as regards stromal cellularity (low/moderate and high), mitotic activity (low and high), p53 expression (low, moderate, high), Ki67 expression (low and high) rates. Statistical correlation amongst the whole parameters were searched with Chi-Square test. Results: Stromal cellularity, mitotic rate, p53 and Ki67 expression rates were all closely correlated (p = 0.000-0.001) for benign and malignant histologic subgroups. Ki67 expression was significantly correlated with histologic subgroups, stromal cellularity and mitotic rate (p=0.000-0.001). Similarly P53 expression was correlated with histologic subgroups, stromal cellularity and mitotic rate (p= 0.000-0.002). Conclusion: Both Ki67 and p53 expression rates are statistically significantly correlated with grade of mammary phyllodes tumors, so they can be used in determination of tumor grade, especially for differential diagnosis of benign and malignant ones.