Breast cancer is the most common cancer among women. This study aimed to determine the disease-free survival and its prognostic factors among Iranian patients. In this longitudinal study, 559 cases of breast cancer were studied. The subjects were registered in Motamed Cancer Institute, Tehran, Iran, during the period 1997-2007 and were followed up to 2013. The data were analyzed using STATA version 11 software. The results of this study showed that lymph node involvement and tumor size were associated with disease-free survival time. The group with lymph nodes involvement had an odds of survival 55%   lower than the other group (P = 0.01). With one unit increase in the tumor size, the odds of survival decreased by 53% (P < 0.001). Level of education, type of surgery, ER, and age was not identified as prognostic factors. The impact of lymph node involvement and tumor size on survival is verifying the importance of early detection of the disease, the need for awareness of women and the implementation of screening programs in this regard.