The true pathological T3N0M0 breast cancer is a rare disease with surprisingly good survival rate. In this retrospective study we tried to evaluate the possible prognostic factors in pT3N0M0 breast cancer patients and to compare them with pT3N1M0 and pT1-2N0M0 patients. Between December 1993 and December 1998, 444 patients without any distant metastases were treated at our department. A total of 194 patients were staged as pT3. Among them 40 were pT3N0 and 154 were pT3N1. One hundred patients were staged as pT1-2N0. The 3-year overall (OS) and disease free survival rates (DFS) for T3N0M0 patients with a median follow-up time of 38 months are 100% and 90%, respectively. There was no statistically significant DFS and OS difference between T1-2N0 and T3N0 patients. A significant DFS, distant metastasis free survival (DMFS) advantage was observed in T3N0 subgroup when compared to T3N1 patients. Although not significant, there was a strong trend for OS in favor of T3N0M0 patients as well (p=0.09). For T3 patients, the metastatic lymph node ratio (LNR: number of metastatic lymph nodes/total number of lymph nodes dissected) significantly affected both DFS and DMFS; however there was no significant survival difference between 0% and 1-25% LNR groups both in terms of DFS and DMFS. These results suggest that T3N0M0 breast cancer patients treated by postoperative radiotherapy and chemotherapy have a fairly good outcome comparable to T1-2N0M0 patients. A subgroup of T3N1 patients with less than 25% lymph node involvement seems to behave similarly to T3N0 patients.