: Background : Serum appearance of anti-p53 antibody (p53Ab) has been reported as an indicator for progressive potential of human tumor tumors including breast cancer. But its significance in breast cancer has not been discussed fully. Methods : Relationship between serum appearance of p53Abs and representative data accounting for progressive potential in breast cancer, nuclear grade (NG), triple negative cancer, and the cumulative score based on these two data (TGS) was investigated among 129 women with invasive ductal carcinoma (IDC) of the breast, who had been treated with surgical resection. Results : There was a significant correlation between appearance of p53Abs and recurrence of the tumors (P = 0.035). Significant correlation of serum appearance of p53Abs with negative expression of ER (P = 0.011), the proportion of TNBC (P = 0.013), NG (P = 0.017), and TGS (P = 0.0005). Conclusions : Preoperative serum appearance of p53Abs can be correlated with pathological nuclear grade, incidence of triple negative breast cancer, and TGS. These results might demonstrate more powerful significance of serum appearance of p53Abs as an indicator of progressive potential in IDC of the breast.