Background and Aims: Breast cancer is one of the leading causes of mortality in Indian women. Although breast cancer is an epithelial malignancy, stroma plays a key role in its development and pathogenesis. Stromal markers are now emerging as novel markers in assessing the prognosis of invasive breast cancer and have not been studied extensively till date. The aim of the present study is to study the stromal expression of CD10 in breast carcinoma, find its relationship with other prognostic markers and study the role stroma plays in breast cancer pathogenesis. Materials and Methods: A total of 70 cases of breast cancer were included in the study. Representative sections were taken and hematoxylin and eosin staining was done. Immunohistochemistry was performed with ER, PR, Her2neu and CD10. Stromal expression of CD10 (>10% stromal positivity was considered positive) in invasive breast carcinoma was noted and was statistically analyzed with different known prognostic markers of breast carcinoma. Results: Stromal expression of CD10 was found to be significantly associated with increasing tumor grade (P = 0.04), increasing mitotic rate (P = 0.33), worsening prognosis (P = 0.01), ER negativity (P = 0.0001), Her2neu positivity (P = 0.19) and with molecular subtypes (CD10 positivity with the HER2 type, and CD10 negativity with Luminal type). No correlation was found between CD10 overexpression and PR, age, menopausal status, tumor size, lymph node positivity and tumor stage. Conclusions: This study gives substantial proof to the various models/research papers explaining the role of stroma/CD10 in breast cancer pathogenesis. Keeping the role stroma plays in predicting prognosis and tumor response, CD10 should be included as a routine pre-chemotherapy marker in breast carcinoma. Further studies should be performed to see the role stroma plays in hormonal expression and the usefulness of CD10 to predict treatment failure in breast carcinomas receiving neoadjuvant therapy.