Purpose: Recently, molecular subclassification of breast carcinomas has been proposed as a new prognostic parameter. Methods: We classified 222 invasive breast carcinoma cases in 5 molecular subtypes by using tissue microarray (TMA) and immunohistochemistry methods. These subtypes were luminal A (estrogen receptor/ER and/or progesterone receptor/PR positive), luminal B (ER and/or PR positive + HER2 positive), HER2-expressing type (ER and PR negative, HER2 positive), basal-like type (ER, PR and HER2 negative, positive with at least one of these myoepithelial markers: CK5/6, CK14, EGFR) and null type (ER, PR, HER2 and myoepithelial markers negative). We compared these subtypes according to their clinicopathological features and GATA3 expression. Results: Luminal A was the most frequent subtype. According to overall survival rates, HER2-expressing and basal-like types had the worst prognosis, while luminal A had the best. However, luminal B had the worst prognosis according to disease free survival. Most of the squamous differentiated metaplastic carcinomas were basal-like type. Tubular and mucinous carcinomas were luminal A. Most basal-like tumors were grade III. The majority of grade I tumors were luminal A. GATA3 positivity was associated with low grade tumors and luminal A subtype. Conclusion: Molecular classification can be accepted as an independent prognostic factor for invasive breast carcinomas. GATA3 expression was associated with luminal A and low histological grade. However, it wasn't shown as an independent parameter. © 2010 Zerbinis Medical Publications.