PURPOSE: The favorable types of the breast cancer-medullary, mucinous, papillary and tubular carcinoma are uncommon subtypes and their incidence in different series ranges between 2.0% and 8.0%, 1% and 2%, 0.3% and 3%, less than 2% of all breast cancers respectively. It has been reported that in western countries they have good prognosis and slow growth rate. Clinically, these tumors have lower frequency rate of axillary nodal involvement and better 5-year or 10-year survival rate than the other common type of breast cancer. MATERIALS AND METHODS: To determine the clinical characteristics and to evaluate the correlation between the progrostic factors and survival rate of these tumor, the medical record of 83 women with medullary, mucinous, papillary and tubular carcinoma treated at Korea Cancer Center Hospital between Jan. 1987 and Dec. 1997 were reviewed retrospectively. RESULTS: The incidences of medullary, mucinous, papillary and tubular carcinoma were 0.51%, 1.45%, 0.71% and 0.14% of all breast cancer respectively. There were 1 case of local recurrence and 5 cases of systemic relapse during the period of follow-up (median follow-up period of 56 months). Overall 5-year survival and 10-year survival rate were 98.5%, and 94.2% respectively. No significant difference in overall survival rate was detected according to histologic type of these tumors but disease-free survival was significantly lower in papillary carcinoma than the other types of these tumors (p=0.042). Standard prognostic factors of breast cancer such as tumor size, lymph node status, age of the patient and ER status did not affect the prognosis of these tumors. CONCLUSIONS: Medullary, mucinous, papillary and tubular carcinoma revealed very excellent prognosis in this study regardless of tumor size, lymph node status, age of the patients and ER status.