We report 4 new cases of breast carcinoma in teenage girls diagnosed by use of histochemical and immunohistochemical methods. These cases of breast carcinoma in women under 20 years of age were found in the files of our department in the last 24 years (1976-2000). The patients had operable breast carcinomas corresponding to various histologic types (1 invasive ductal carcinoma associated with fibroadenoma, 2 secretory carcinomas, and 1 invasive lobular-type carcinoma). Simple mastectomy with low axillary lymph node dissection was performed in 2 postpubertal patients. Only 1 patient received adjuvant chemotherapy (case 4). After follow-up ranging from 76 to 126 months, 3 patients are alive and disease-free and 1 has disseminated metastatic disease. The correlations with prognosis-related risk factors (stage, age, previous benign lesions, family history, histologic types, hormonal receptors, and pregnancy) were examined.