To investigate the expression of vacuole membrane protein 1 (Vmp1) and its prognostic value in invasive ductal carcinoma (IDC) and concomitant ductal carcinoma in situ (DCIS) of the breast.The expression and location of Vmp1 in the breast tissues from 102 patients with IDC and 32 concomitant DCIS were detected by immunohistochemical SP method, and the relationship with clinicopathologic parameters was analyzed.Vmp1 expression was observed in the cytoplasm of the cancer cells in 57.8% (59/102) cases, and correlated with grade (χ(2) = 12.644, P = 0.002), pTNM stage (χ(2) = 11.987, P = 0.001), node status (χ(2) = 9.341, P = 0.002), tumor diameter (χ(2) = 7.630, P = 0.022) as well as Nottingham Prognostic Index (NPI;χ(2) = 15.561, P = 0.000). The expression of Vmp1 in concomitant DCIS was higher than that in IDC (81.3% vs 56.3%; χ(2) = 4.655, P = 0.031). In this cohort, the mean disease-free survival was 81.2 months; the 5-year overall survival rate was 90.2% (92/102) and the disease-free survival rate was 81.4% (83/102). Vmp1 expression had significant influence on disease-free survival time, with Vmp1-negative patients showing poor prognosis (χ(2) = 11.192, P = 0.001). COX's proportional hazards regression model revealed that Vmp1 was a protective factor, with relative risk < 1.The detection of Vmp1 in IDC may be helpful for prognosis prediction; the patients with Vmp1 expression may have a better prognosis.