摘要Objective: To study the significance of histological grading as a prognostic factor in ductal carcinoma in situ of the breast. Methods: According to the Van Nuy's classification, 32 cases of ductal carcinoma in situ (DCIS) of the breast were divided into three groups. Results: Low grade (well differentiated, low grade DCIS) 12 patients (37.5%); Intermediate grade, 9 patients (28.1%); High grade (poorly differentiated DCIS) 11 patients (34.4%). Among the high grade DCIS, the histologic subtypes were comedo (9 patients), micropapillary (1 patient) and solid (1 patient). The positive expression of c-erbB-2, p53 and MIB-1 in high grade DCIS was higher than that in intermediate and low grade DCIS. The difference between high grade and low grade DCIS was significant (p<0.05). The expression of ER in high grade DCIS was lower than that in intermediate and low grade DCIS. Conclusions: Histological grading of breast ductal carcinoma in situ may be a good prognostic factor.